JPS6189560A - Apparatus for operating amplitude value - Google Patents

Abstract

PURPOSE:To attain to operate an amplitude value at a high speed from the differential value of a sampling value, which was obtained by using sampling values having different electric angles among sampling values of an AC signal and multiplying one of them by coefficient, and the other sampling value. CONSTITUTION:Two sampling data having different electric angles among sampling data of an AC signal are used and the sampling value of one of them is multiplied by the constant determined by a sampling time and the differential value of the obtained value and the other sampling value is calculated. Then, by utilizing that electric angles of said differential value and the multiplied sampling value are different by 90 deg., a binary addition system is adapted and high speed response to the variation in the amplitude of an input AC signal is enabled.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an amplitude value calculation device, and particularly to an amplitude value calculation device used when performing switching control of a power grid according to the amplitude value of a power grid current or voltage. It is.

[Technical background of the invention]

The amplitude value calculation device samples the AC signal at predetermined intervals of 11], converts the sampled values into digital quantities, and then calculates the amplitude value of the AC signal.

Conventionally, known calculation methods for amplitude value calculation devices include a method using an addition method or a peak value detection method, and a method using a multiplication result such as the square method.

For example, in the case of the square method, it is given by formula (1) from the trigonometric formula.

sin" θ 10 high 20 = S stone 2 θ + S stone 2 (θ + -) = 1
(1) As is clear from the above equation (1), the square value of the amplitude value can be obtained by calculating the sum of the squares of two sampling data whose electrical angles differ by 90°.

This method is advantageous in that errors due to the sampling phase do not occur in principle, but in order to obtain the amplitude value, a square root calculation is required. In general, methods in which calculation results are obtained in a quadratic manner have good calculation accuracy, but require square root calculations as described above, and when these calculations are performed by a calculation device such as a computer, there is a significant disadvantage in terms of calculation time.

On the other hand, there is a binary addition method in which an amplitude value is obtained using two sampling data whose electrical angles differ by 90 degrees, as a method in which calculation results are obtained in the first order.

The principle equation of this system is shown in equation (2), and will be explained with reference to the principle diagram shown in FIG.

In the binary addition method, the AC input signal is 17(t)=Vsfn
When ωt is used, the calculation for determining the amplitude value is given by equation (2).

■□=(1+K)V π=l bt l publication Vain(ωt←) l+Kl l
Vsirlldt l-I Vs=(ωt-17]1
=lVsi+#tl+1Vcoutl+K11Vd#t
l-1'Vcautll ・+・<2) Figure 6 (a)
is a diagram showing l VsWJ t l and 1-tl in equation (2), the added value of both is shown in figure (b), and the absolute value of the difference is shown in figure (c).

Here, if we pay attention to the waveforms in Figure (b) v (C), when one takes the maximum value, the other takes the minimum value, so if we multiply both by an appropriate coefficient K and calculate the force a, we get (d ) As shown in the figure, the variation in the calculation results due to the sampling phase can be reduced.

The optimal value for the coefficient that minimizes the variation is (,/'2
”--1), but in order to facilitate calculation processing on a computer, the value of =1 is normally used. At this time, the calculation error according to equation (2) is ±5.5%, but (2 ) The calculation errors can be suppressed by smoothing the fluctuations by further performing delayed addition n times as shown in equation (3).

lVl=Vm10Vm-1+・・・・・・・・・+V□-
1...3 However, m is a time series.For example, when an AC signal with a frequency of 50 Hz is sampled at a sampling frequency of 600 Hz, the binary addition method will be explained. This is done every 30 degrees.

Therefore, data whose electrical angle differs by 90 from the sampling data intensity at time (In) is data before or after three samplings, and is Z-5 or τ. It is +3. Using this relationship, equation (2) can be rewritten into equation (4).

7m -IVml +IVm-31+Kl lVml
Ivm-xl I - (4) Smoothing of the variation is (5)
As shown in the equation, by adding the results of equation (4) three times in succession, the calculation error can be compressed to +0.61, and sufficient accuracy for practical use can be obtained.

[Problems with background technology]

The binary addition method described above has the advantage of shortening the calculation processing time because the amplitude value can be calculated by simple calculations using addition and subtraction, absolute value calculations, and constant multiplication.

However, in order to obtain accurate calculation results, smoothing $
Therefore, a relatively large amount of data is required for amplitude value calculation. In the above example, the calculation of equation (5) requires six consecutive samplings of data as shown in Figure 7.
For this reason, it has the disadvantage that the response of the deduction result to changes in the amplitude value of the AC signal cannot be made faster.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an amplitude value calculation device that can speed up the response of calculation results to changes in the amplitude value of an AC signal.

[Summary of the invention]

In the present invention, among sampling values of an AC signal, sampling values with different electrical angles are used to obtain a difference value between one sampling value multiplied by a coefficient and the other sampling value, and this difference value and the above-mentioned This method attempts to calculate an amplitude value by applying a binary addition method using sampling frequency multiplied by a coefficient.

[Embodiments of the invention]

Examples will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an embodiment of an amplitude value calculation device according to the present invention. In FIG. 1, 1 is an AC input signal, and 2 is a sampling circuit which samples the AC input signal at an arbitrary frequency and introduces this sampling data into an arithmetic unit 3. This arithmetic unit 3 is composed of a computer such as a microconbeater, and when expressed in terms of function realizing means, as shown in the figure, a difference unit 49, an adder 8s11, a multiplier 5, a coefficient unit 6,
It consists of 7°10. Then, in the subtractor 4, the sampling booter m-1 at time (m-1) and the time (m)
sampling data τ. The nine tones ω multiplied by the coefficient -T
Output the absolute value I'm-1-v-il k of the difference value of T,
On the other hand, the multiplier 5 outputs the absolute value of ig - t l described above.

Here, if vm=Vsfm (ω is 10), then the differentiator 4
The output of the multiplier 5 is expressed by the following equation (6), and the phase relationship between the two is shown in FIG.

'm-1-v-T=Vsin(6)t+θ-QIT)-
Vsin(GJ t+θ)−T=Vsw(ωt+θ−ω
'l') -v-! -(*(ω to 1θ+oT)-)m
(ωt+θ-GET)) As is clear from equation (6) and Figure 4, the difference value and the multiplication value differ by 90 degrees in electrical angle, and this relationship holds regardless of the AC signal frequency, sampling frequency, and sampling phase. .

Furthermore, this holds true not only for two consecutive sampling data, but also for the difference unit and multiplication value of two sampling data at arbitrary times. Numerals 6 and 7 are coefficient units for the sum difference value and the multiplication value, and at least one of them is multiplied by a coefficient in order to equalize the mold widths of both, 1x-1f4.

Here, by setting each constant as in the following equation (7) and multiplying equation (7) by equation (6), the amplitude values become equal.

The adder 8 receives the output k l v(p, -1-
The result of addition of sleepover T l and the output zlvφT1 of the coefficient unit 7, k117m-1-τ-T I +L l 'relativeρT
l't, and the difference unit 9 outputs the output klvm of the coefficient unit 6.
-1-False TI and output of coefficient multiplier 7 zl νm1pT l
Absolute value of the difference between country Vm-+ ”m1pTl-tl
'-Output l l. The output of the difference device 9 is multiplied by a coefficient K in a coefficient multiplier 10, and then added together with the output of the adder 8 in an adder 11 to output a signal Yn1.

This signal Ym is given by the following equation (8).

Ym=kl Tsutomu-1”rrp$Tl+tlυaddition pT l+
Klklvm-1-v-Tl-Llv-Tl l...
--(8) Furthermore, as shown in equation (8), when t is set to equation (7), the following equation (9) is obtained.

Therefore, equation (8) is transformed into equation 90 below.

Ym=l Vcos(ωt+θ) l + l Vs4
(ωt+θ)1+KI I Yens(GJt+θ]−
1vsi,, (ω is 10) l l ・At) The calculation of the equation 00 is the same as the amplitude value calculation shown in Figure 6, and when the coefficient is = JT-1, Ym due to the sampling phase
The variation in the calculation result is minimal, but if the calculation of the αη formula is performed to further smooth the variation, the amplitude value can be determined with high accuracy.

IY1=Yrn+Ym-1+...10Ym
However, according to the above embodiment, the amplitude value calculation in equation (8) can be performed using only two consecutive sampling data.

When sampling an AC signal with a frequency of 50 Hz at a frequency of 600 Hz, the conventional method required 4 samplings as shown in equation (4) to obtain sampling data of 90 degrees electrical angle. Since the present invention requires only two samplings, it is possible to double the response time of the amplitude value calculation value. In addition, when smoothing the calculation result by three consecutive additions, the conventional method required 6 samplings, but the present invention requires only 4 samplings as shown in Figure 3, which reduces the response time. It is possible to increase the speed by 1.5 times. Also, electrical angle 9
Even if 0° data cannot be obtained directly from sampling data, according to the present invention, data with electrical angles that differ by 90° can always be obtained regardless of the AC signal frequency, sampling frequency, and sampling phase, so it is convenient for application. There are fewer restrictions.

In the above embodiment, a case is shown in which the next sampling data in time series out of two consecutive sampling data is multiplied by the coefficient T, but the method is not limited to this and the following method may be used.

As shown in FIG. 4, two consecutive sampling data vm-1pν. Among them, the previous sampling data in the time series is multiplied by the coefficient couT, and the absolute value of the differentiator 4 is 1vm-
υm-1co#Tl and the absolute value of multiplier 5 1'%-1c
Calculate using c$T l.

In this case, the following equation (2) can be obtained by performing the same transformation as above.

vm-vm-+co#T=shi(ωt+θ)-Vsin(
ωt+θ−ωT) Go! IJT=vsil(ωt+θ
) VJs stone (ωt+θ)−hhx(ωt+θ−2ω
T)) The above four equations can obtain sampling values different by 9σ, similar to the above equation (6). Therefore, high-speed processing is possible and highly accurate amplitude value calculation is possible.

As shown in FIG. 5, among the sampling data vm-2 two sampling times before and the sampling data after the time series are multiplied by a coefficient dωT, and the absolute value of the difference unit 4 is 1 sm-2- The contribution ωTl is the absolute value I'y of the multiplier 5
2ωT l.

In this case as well, the following equation 03 is obtained by performing the same transformation as above.

υm−2−vmect+T==Vs+n(” t+θ−2
ωT)−Vsin(ωt+θ)dωT=vsir, (ω
t+θ-2ωT )-1 ke(stn(ωt+θ+2ωT
)-hln(ωt+θ-2ωT)1 The above C1j equation, like the above-mentioned equation (6), allows sampling values different by 90° to be obtained, thus achieving the same effect as described above.

〔Effect of the invention〕

As explained above, according to the present invention, among the sampling data of an AC signal, one sampling value of two data having different electrical angles is multiplied by a constant determined by the sampling time, and the difference value from the other sampling value is calculated. Since the two-value addition method is applied by taking advantage of the fact that the electrical angles of both the sampling value and the multiplication sampling value differ by 90 degrees, it is possible to apply the binary addition method to It is possible to provide an amplitude value calculation device capable of high-speed response.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the amplitude value calculation device according to the present invention, FIG. 2 is a diagram showing the vector relationship between sampling data and its difference value multiplied by 9, and FIG. 3 is a diagram showing the vector relationship between sampling data and the calculation result. Figures 4 and 5 are vector diagrams showing modified examples, Figure 6 is a diagram explaining the principle of the binary addition method, and Figure 7 is sampling data used in the conventional binary addition method. FIG. 1... AC signal 2... Sampling circuit 3... Arithmetic device 4, 9... Differentiator 5...
・Multiplier 6, 7.10... Coefficient unit 8/1
1...Adder view 2 figure 3 figure 4 figure 5 figure 6

Claims (1)

[Claims] a circuit that samples an alternating current signal at predetermined time intervals;
Two different electrical angles output from this sampling circuit
a multiplier that multiplies one of the two sampled values by a predetermined constant and calculates its absolute value; and a multiplier that calculates the absolute value of the difference between the other sample value and the value obtained by multiplying the one sample value by a predetermined constant. a first adder that multiplies at least one of the output value of the multiplier and the output value of the first difference device by a predetermined constant, and then calculates the sum of the two, and a difference between the two. a second difference device for calculating a value; and a second difference device for calculating an added value of the two after multiplying at least one of the output value of the first adder and the output value of the second difference device by a predetermined constant. An amplitude value calculation device comprising: an adder; and an adder.