SU1580276A1 - Digital meter of coefficient of harmonics - Google Patents

Abstract

This invention relates to electrical measurements and can be used to measure harmonic coefficients. The purpose of the invention is to simplify the technical implementation. The meter contains analog-to-digital converter 1, quadrants 2 and 7, adders 3, 8 and 9, block 4, block 5, extraction of square root, digital filter 6, scaling blocks 10 and 11, driver 12, frequency multiplier 13, block 14 of control . The introduction of new links reduces the number of blocks used. 3 il.

Description

eleven

L 1

1

This invention relates to electrical measurements and can be used to measure harmonic coefficients.

The purpose of the invention is to simplify the technical implementation of a digital harmonic coefficient meter.

FIG. 1 shows a block diagram of a digital harmonic coefficient meter; in fig. 2 is a functional block diagram of the control j in FIG. 3 - amplitude-frequency characteristic of the digital filter.

The digital meter contains serially connected analog-digital converter 1, first quad 2, first adder 3, block 4, block 5, the square root extractor 5, with the first input of analog-digital converter 1 connected to the input of the device and also to the input of the imager 12, the output of which is connected to the input of the frequency multiplier 13 and to the first input of the control unit 14, the outputs of which are connected to the corresponding control inputs of the analog-digital converter 1, the first quad 2, the first adder 3, b 4 dividing unit, 5 square root extraction unit 5, as well as the second quadrant 7, the first and second scaling units 11 and 10, the digital filter 6, the input of which is connected to the output of the analog-digital converter 1, and the output with the successively included second quadrant 7, the second adder 8, the third adder 9, the second scaling unit 10, the output of which is connected to the second input of the dividing unit 4, while the control inputs of the second quadrant 7, the second and the third sz mmator 8 and 9, the first and second scaling blocks 11 and 10 and digitally The first filter 6 is connected to the corresponding outputs of the control unit 14, the input of the first scaling unit 11 is connected to the output of the first adder 3, and its output is connected to the second input of the third adder 9, the output of the frequency multiplier 13 is connected to the second input of the control unit 14.

Digital filter 6 is an arithmetic unit implemented by

known dependence m m

,

(one)

where Xj - input digital codes;

Y, - output digital codes; (., ft, are filter coefficients determining the type of its amplitude-frequency characteristic; m is the order of the filter; i is the number of the input (output)

digital code.

The control unit 14 contains a clock pulse generator 17, the output of which is connected to the synchronization input of register 16, whose information output, which is the address of the microcommand, is connected to the address input of the memory element 18, the outputs of which form microcommands and they are distributed as follows: YI - YII are outputs of control unit 14, Y12 and Y13 are connected to the control inputs of the multiplexer 15 conditional transitions, Y6 is connected to the first information input of the register 16, as well as to the first information input of the multiplex A conditioner jump 15, the output of which is connected to the second information input of the register 16, the second and third information inputs of the multiplexer 15 conditional transitions are the inputs of control unit 14. The digital meter works as follows

In the initial position, the memory elements of the adders 3.8 and 9 are in the zero state. The analyzed signal Uy is fed to the input of the imager 12 which produces one pulse for the period of the signal Ux at the moment of the signal’s transition through zero, and to the information input of the analog-digital converter 1. The output pulses of the imager 12 are fed to the first input of the control unit 14 and to the input of the multiplier 13 pulse frequency, the output of which is fed to the second input of the control unit 14. The impulse from the output of the imaging unit 12 starts the control unit 14 to measure one period. During this time, N pulses come to the second input of control unit 14 from the frequency multiplier 13 output (where N is the frequency multiplier multiplier), which start the block at times t 2 / t / i (, ..., N). The control unit 14 for each pulse of the multiplier generates a sequence of pulses on the ADC 1, quadrants 2 and 7, digital filter 6, the first

515

and second adders 3 and 8 for converting and processing one discrete signal U, v. The codes of the instantaneous voltage values of the signal under study from the output of the analog-digital converter 1 are fed to the input of the first quadrant 2. The squared codes of the instantaneous values are summed in the first adder 3. At the same time, the same codes from the output of the converter 1-. step on the input of the digital filter 6. The frequency response of the digital filter 6 is determined by the coefficients d. , j}: according to implementation

filter by the formula (1) and is chosen in such a way that for the first (main) harmonic component the transmission coefficient of digital filter 6 is equal to K ,, and for the second, third and so on harmonic components of the input signal the transmission coefficient of digital filter 6 is equal to K2 , and, i.e. digital filter 6 is a blocking filter (Fig. 3). The given suppression width 52. near the first harmonic can be ensured by setting the corresponding coefficients tfj, f3; digital filter. The introduction of a sufficiently wide band allows the device to be uncritical to tuning to the frequency of the input signal in the interval (CO, G), +9/2). The codes converted by the digital filter 6 are fed to the input of the second quadrant 7, from the output of which the squared codes are fed to the input of the second adder 8 and summed therein. For one period of the signal under study, codes that are proportional to the square of the effective value (i.e. power) are fixed in the first adder 3

follow signal

(t;

where P is the code stored in the first adder 3;

P is an estimate of the total input power Ujj.50. At the same time, in the second adder 8, a code proportional to the value of P determined by the ratio

45

P k2p + k2P

G251 1 LH 1 2X

(3)

where P is the power estimate of the first harmonic component of the input signal;

P is an estimate of the power of all higher harmonic components of the signal, starting with the second. After completion of the formation of the codes P and P by a signal from the control unit 14, at the output of the first scaling unit 11 a code P will be generated, defined by the ratio

(four)

After the formation of the codes P / yjP y from the signals coming from the control unit 14, the codes P. and

step on the summing and subtracting inputs of the third adder 9, respectively. As a result, a code proportional to the power of all the harmonic components of the signal is formed in the third adder 9, starting from the second

(five)

. -H-

The code of the third adder 9 by the signal from the control unit 14 is supplied to

the input of the second scaling unit 10, in which this code is multiplied by a constant coefficient (). The code formed at the output of the second scaling block 1P is determined from the ratio

(k22-k. (6)

According to the next signal from the control unit 14, the codes from the output of the first adder 3 and the second scaling unit 10 are fed to the corresponding inputs of the division unit 4. The code at the output of block 4 division is proportional to the ratio of the power of higher harmonics,

starting from the second to the full signal power

К Р $ Mel РЈ Р The received code from the output of block 4

(7)

50

45 divisions are fed to the input of the square root extraction unit 5. The code formed at the output of the square root extraction unit 5 is equal to the harmonic coefficient of the signal under study.

K, HKS. | E, -KG.

Claims (1)

Thus, by reducing the number of blocks used, the technical implementation of a digital harmonic coefficient meter is simplified. Invention Formula Digital harmonic coefficient meter containing the first scale715802 enclosing unit, serially connected analog-to-digital converter, first quad, first adder, dividing unit, extraction unit square root, serially connected digital filter, second quad, second adder, third adder, second scaling unit, serially connected shaper and frequency multiplier, as well as a control unit, the first input of which is connected to the driver output, and the outputs are connected to the corresponding controls input inputs of the first and second jj quad quadrants, the first, second and third adders, the first and second scaling blocks, the division unit, the root extraction unit square 4 15 y- sixteen 17 2 eight digital filter whose input is connected to the output of an analog-to-digital converter, whose input is connected to the input of the device and the input of the former, and the output of the second scaling unit is connected to the second input of the division unit, characterized in that the first scaling unit is connected to the output of the first adder, and the output is connected to the second input of the third adder, the output of the frequency multiplier is connected to the second input of the control unit, and the second input of the analog-to-digital converter The paddle is connected to the corresponding output of the control unit. PP У1 Кпоз.1 Y2 K vines. 2 - UZ Kpoz.Z - U4 K POS 4 18 5 K L03 5 Y6 K to 36 Y7 to po.i: Y8 TO REF. eight Y9 VU K PO 2, 9 K L O3.10 Y11 CL03.11 Y12 Y15 TO H Q Have I I I I Ji with Phys.d B) $ b) b)