SU1486950A1 - Method and apparatus for determining phase difference between current and voltage of symmetrical three-phase system - Google Patents

Description

The invention relates to a measuring technique and can be used to register the phase difference between the current and voltage of a symmetrical three-phase system. The purpose of the invention is to increase the speed of obtaining information about the instantaneous value of the phase difference. The application of the invention allows to obtain a continuous signal proportional to the instantaneous value of the difference at the appropriate point in time. The dependence of the received information on the frequency of the investigated signals is eliminated, since the procedure for obtaining this information is based on a comparative analysis of the instantaneous values of the investigated signals and on the time intervals corresponding to their position. Information about the moment

The actual value of the phase difference can also be obtained in transient conditions. Increases the speed and accuracy of obtaining information about the value of the phase difference at a given point in time. 2 sec. f-ly, 5 ill.

The invention relates to measuring equipment and can be used for registering the phase difference current and voltage three-phase system balanced _h.

The purpose of the invention is to increase the speed of obtaining information about the instantaneous value of the phase difference.

FIG. 1 - 3 shows the dependences of the current value of the phase c / _and = co in the first voltage phase, the ratio of the instantaneous voltage value of the first phase to the instantaneous voltage value of the second phase (Fig. 1), the instantaneous voltage values of the first, second and third phases (Fig. 2 ), the ratio of the instantaneous voltage value of each next phase to the instantaneous voltage value of the preceding phase (Fig. 3); in fig. 4 is a block diagram of an apparatus for measuring a phase difference between a current and a voltage of a symmetrical three-phase system; in fig. 5 - timing diagrams that explain the operation of the device.

A device for determining the phase difference consists of 1 to 3 symmetric three-phase systems included in each phase, respectively

00

05

Yu

cl

3

1486950

four

sensors 4-6 phase_currents and sensors _: 7 ~ 9 phase voltages D - 3 respectively The outputs of sensors 4-6 currents are connected to three inputs of the I0 block determining the instantaneous phase value of the first phase of the current, and the outputs of the voltage sensors 7-9 are connected to three inputs of the block 11 determine the instantaneous phase value of the first phase voltage. Blocks 10 and 11 are identical. Each of them is based on the example of the 1TG block for determining the instantaneous phase of the first phase of the current, containing the first, second and third drivers 12-14 pulses, the inputs of which are connected to the inputs of the first, second and third inverters 15-17, respectively, and the inputs of block 10; the first, second and third elements NOT 18-20, connected by their inputs to the outputs of the first, second and third drivers 12-14 pulses, the first, second and third blocks ^ 21-23 divisions, the inputs corresponding to the dividend, which are connected to the inputs the first, third and second formers respectively

12, 14 and 13 pulses, and the inputs corresponding to the divider are connected to the outputs of the second, first and third inverters 16, 15 and 17, respectively. And also the first, second, third, fourth, fifth and sixth elements 24 are 29 matches.

The output of the first driver 12 pulses is also connected to the first inputs of the first, third and fifth elements 24, 26 and 28 matches, and through the first element NOT 18 to the first inputs of the second, fourth and sixth elements 25, 27 and 29 matches. The output of the second shaper 13 pulses connected to the second inputs of the fourth and fifth elements 27 and 28 of the match, and through the second element is NOT the 19th second inputs of the third and sixth elements 26 and 29 of the match. The output of the third pulse shaper 14 is connected to the second input of the first coincidence element 24 and to the third coincidence input 27, and through the third element NO 20 to the second input of the second coincidence element 25 and to the third input of the third coincidence element 26.

In addition, block 10 contains the first, second and third adders 30 32, the first inputs of which are connected respectively to the outputs of the first, second and third division blocks 21-23. In this case, the second input of the second adder 31 is connected to the output of the reference voltage unit 33, to the input of the first large-scale amplifier 34, the output of which is connected to the second input of the third adder 32, and to the input of the second large-scale amplifier 35.

The outputs of the second and third adders 31 and 32 are connected to the first inputs of the fourth and fifth adders 36 and 37, the second inputs of which, together with the second input of the first adder 30, are connected to the output of the second large-scale amplifier 35. Unit 10 contains the first, second, third, the fourth, fifth, sixth 38 43 keys and the sixth adder 44, six inputs of which through the first, second, third, fourth, fifth and sixth keys 38 - 43 respectively are connected respectively to the outputs of the first division 21, first, second, fourth, third and fifth adders 30,31,36., 32 and 37. The control inputs of the first, second, third, fourth, fifth and sixth keys 38 - 43 are connected to the outputs of the first, second, third, fourth, fifth and sixth, respectively, elements 24 - 29 of the match. The output of the sixth adder 44 is connected to the output of the unit 10 for determining the instantaneous phase value of the first phase of the current and is connected to the subtractive input of the algebraic summing unit 45, the first summing input of which. connected to the output of block 11 for determining the instantaneous phase of the first voltage phase, and the second summing input through the seventh switch 46, the control input of which is connected to the output of the comparator 47 connected by its inputs with the output of blocks 10 and 11, and the third large-scale amplifier 48 is connected to the output of the second large-scale amplifier 35 of the block 10. The output of the block 45 algebraic summation is connected to the input of the recording unit 49.

The instantaneous value of the phase difference <Hb) between the current and the voltage of a symmetrical three-phase system can be determined as follows

h ’(b) = (O

where </ (С) and ¢ / () :) are the instantaneous value {

phase of the first phase, respectively, voltage and current "

The instantaneous value of the first phase, V-phase voltage and the instantaneous value of the current phase of the first phase are defined similarly to "For example, for a symmetric system of the first voltage II _((e), the second on February ₁₁ (c) and the third and _s (¢) can be determined by expressions phases

11, (0 = and _m βίηωε = υ ^ ίη ^ ίΟ,

(2)

and _r (r) = and _f 9sp (s) C - 21Γ / 3) =

= and _t 81n (q> _and (c) -2? / 3); (3)

and ₃ (g) = and _m 3ίη (ώτ + 217 / h) =

= υ _Μ 8ίη (P> _and (1 :) + 2TG / 3), (4)

where and - the amplitude of the phase voltages;

ω is their angular frequency.

If expression (2) is divided by (3), then we obtain an equation that can be represented as a function depending on the instantaneous value of the phase (/ _i (s) of the first phase in this case of voltage

_β __________ _{_}

υ ₂ (ί) 3ίη (ιγ _Μ (τ) - 2 17/3)

“ΊС (5)

Dependence of the relation of tension to υ _? (ε) in the function ι /, / ε),

calculated in accordance with (5), is presented in FIG. 1 for the positive half-period Π ₁ (ί;) at 0 4 ( _pm (r) 4 1 ?. On the negative half-period 11, ((:) at 5 4 4s> _and (G.) 4 21G, the dependence is similar.

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The analysis of the dependency shown in FIG. 1 shows that it has a practical linear EM section when changing </ _m (s) from zero to

.5 m / 3 rad "And (5) can be approximated by the expression

11, (1:) / 11 ₂ (С) = К <Г _И (С), (6)

ten

where the coefficient of proportionality K is determined from the condition that at II, (c) / and ₂ (g) = -1, 1G _And (b) = ^ / h, i.e. K = -3/57,

15 As a result, the dependence is instantaneous. foot, the values of fa ^a1 ' ¹ cf _m (1 :) in the segment 0 ί ι / _Μ (ί) ^ / 3 can be defined as

²⁰ ν _Μ (Ο = -C / g / 3) · <c) / and _g (e). (7)

As follows from the timing diagram of a symmetric three-phase system of voltages 11, ((:) (2), 1Ι ₂ (ί :) (3), υ ₃ (Γ) (4), which is shown in Fig. 2, when the instantaneous value phase one in

within _{17/3 ί ψ μ (ί :) ί} 217/3 prepared analogous to (7), the dependence, if we take _e ratio and (c) to 11. ((:), and the origin place to the point _<m (c) = 7? / 3, and so on »

Thus, if in the areas of change in the instantaneous value of the phase

35 c _and (c) corresponding to 0 4 9> _n (c) 4 4 ίτ / 3; 17/3 4 ^ _AND (O £ 2 1? / 3, '

2 77/3 4 у „(О 4 ί? (Fig. 2), take from the wearing of the voltage indicated by a dashed line in Fig. 2 to a voltage of ⁴ θ, indicated by a thick solid line in Fig. 2, dependence of these relations in funktsiiς> _H (G) as shown in FIG. 3, which easily get ⁴⁵ ^ dependence "(About

17 _m '(O

- (ί? / 3) and, (c) / and _g (ί) with O έ άί / 3;

17/3 - (ίΓ / 3) υ ₃ (Ο / υ, (at Г / З 4 (/ „4 2 17/3; (8)

, 217/3 - (17/3) · and ₂ (s) / and ₁ (C) with 2? / 3 £ ί / _μ 4 57,

At the same time, on the positive half-period! ,,. (() The first part of the change of h ” _and ((:) expressions (8) 0 4 (/„ (! :) 4 4 (? / 3 can be defined (Fig. 2) , if the sign of II ₃ (d) coincides with the sign of u, (1?) (£1 £ n And ₃ (£) = δΐβη и., ((:));

the second segment with 17/3 4 I / „(·" -) 4 4 2/7 / 3, if the signs 11 ^ (1 :) and υ ₃ (ϋ) do not simultaneously coincide with the sign υ, (Γ.) (δΪ2η 1Ιι (Γ.) = Δίβη and ₃ (s) /

/ βίβη and, ((:)); the third section at 2 57/3 4 1 / _m (s) 417, if the sign is H ₂ (s)

7 1486950 ’. eight

coincides with the sign 11, (1 :) (v18pi (s) = - δϊβη II TO) (Fig. 2),

To obtain the instantaneous value of the phase of the first phase voltage and _} (c) on its negative semiperiod, it is also necessary to use (8), having previously inverted g),

and ₂ (b), ΙΙ ₃ (ϋ), and add to the result a value equal to? glad;

As a result, the instantaneous value of the phase ι / BEFORE the first phase in this case, the voltage on the period can be determined by the expression

z id O ί7 P <(b)

z'id'o

NGOs and subsidiaries

? N • s ‘ido

with and ’({;)> 0 '

with (O. about.

with and, (O> o with and, (O <o _

5ΐ§η ido = δΐ§η IDS)

_{5ΐ§η υ ί (ί) = δίβη} υ ₃ (ϊ) ψ ί δί ^ η υ ₃ (Ο

(9)

2ΐ _ ΐ 'Ido • 3.3 Ido

21/5? ido

• z z .ido

with ido> o ’

at and, (Oh <. about

δίβη ido = 81§p ido

Similar to (9), you can determine the instantaneous phase value of the first phase of the current, after which, in accordance with (1), you can get the instantaneous value of the phase difference </ (O ·

It should be noted that in the industry, consumers of three-phase systems are mainly active-inductive loads, when the strainer lags behind the voltage. In that

In the 25th case, there are moments corresponding to a change in ι / DO from zero to a value equal to the phase difference I / (t), when ί / DO turns out to be less (/, (O. To get the actual phase difference of TO before (/ DOD </ TO necessary to the result obtained according to (1) add _about 21Grad, t "e., the phase difference (p (C) should be determined by the expression of the form

35, '

1 / (ί)

1 / TO at 1 / _and (1) 7 (/. (C),

CH'Db) ⁺ ? D at (/ TO <</ TO ·

(ten)

40

The method of determining the phase difference between the current and voltage of a symmetrical three-phase system is based on the specified procedure and includes the operations of determining the instantaneous values of the 45 currents and voltages of all three phases of a symmetrical three-phase system

and, (1 :), ido, iDO, xD), MO, xDr). Then, using 5. BEFORE ί ^ (ϋ), xDO, find the instantaneous phase value (f.) Of the first phase of the current ϊ, (Ο, ^and π using P, (O, and BEFORE, Pz (g) - the instantaneous phase value </ BEFORE the first phase of the voltage PDO, then compare (/ UP 55 and (/ UP and ^) (/ UP ⁷ ) determine the instantaneous value of the phase difference TO, subtracting the instantaneous value of the phase (p. (g .) first phase of current ^: '

xDO from the instantaneous value of phase 1 / BEFORE the first phase of the voltage of the PDO, and with ’(/ TO <(/ BEFORE), the result of subtraction is added to a signal proportional to 2ΐι rad.

The procedures for determining signals proportional to the instantaneous value of phase I /. (T) the first phase of the current xDg.) And the Instantaneous Phase value (/ TO the first phase of the voltage ϋ TO are similar and include the following operations ,, Signals proportional to, for example, the instantaneous values of the first ϋ (ϋ), second xDd) and the third ^ ( About ¹ phase, their signs are inverted and simultaneously determined, and the instantaneous value of the phase (/ TO the first phase of the current D (O is determined in accordance with (9) at x, (c) 7 0,

9

1486950

1 o

'as the quotient from (c) by the inverted 5. ₂ (С), if the sign ₃ (ΐ :) coincides with the sign 1, (1 :), as the quotient from the division of x _e (n) by the inverted 1, (1 :) followed by the addition of the result of division with a signal proportional to 7? / 3 happy ₀ , if the signs ₅ (s) and ί ₃ (ϋ) do not simultaneously coincide with the sign!., ((:) and, as a quotient from division 1 ₂ (с) on the inverted ϊ ₃ (g) with the subsequent addition of the result of division with a signal proportional to 2 ?? / 3 glad, if the sign ₂ (ί;) coincides with the sign 1 ^ ((:), and with, (£) <<0 - similarly, but with the addition of the signal to the result, proportional 1? glad.

A device for determining the phase difference between the current and voltage of a symmetric three-phase system (FIG. 4) works as follows.

The signals P ₊ , II ₅ , II ₆ (fig, 5), proportional to the current, m first 1 (x), second 2 (x ₂ ) and third 3 (x ₃ ) Phases of a symmetrical three-phase system (Fig. 4), with output Sensors 4-6 phase currents are fed to the input unit 10 to determine the instantaneous phase value of the first phase of the current. At the same time, signals proportional to the voltages of the first 1, second 2 and third 3 phases of the same system are input to the unit 11 for determining the instantaneous phase value of the first voltage phase.

The operation of blocks 10 and 11 is similar and the example of block 10 is as follows.

The signal and ₊ (and ₇ ), proportional to the current x, (voltage and,) of the first phase 1, is fed to the inputs of the first driver 12 pulses, the first inverter 15 and the input corresponding to the dividend of the first division 21. The signal Η ί (ΙΙ ₈ ), proportional to the current ΐ _g (voltage And ₂ ) of the second phase 2, is fed to the inputs of the second driver. 13 pulses, the second inverter 16 and the input corresponding to the dividend, the third block 23 division. The signal II _έ (υ ₃ )> is proportional to the Current x ₃ '(the voltage of the third phase 3 is fed to the inputs of the third driver 14 pulses, the third inverter 17 and the input corresponding to the dividend of the second division 22.

At the same time at the inputs corresponding to the divisor of the first, second, and third blocks 21-23 division; the output of the second, first, third inverters 16, respectively;

15 and 17 receive inverted signals proportional to the current x ₂ (voltage L ' ₂ ) of the second phase 2, current ϊ, (voltage I,) of the first phase 1 and current x ₃ (voltage P _e ) of the third phase 3, respectively. the first, second and third division blocks 21–23 divide, respectively, the signal proportional to the current ί, (voltage II) of the first Phase 1, into an inverted signal proportional to the current x ₂ (voltage H ₂ ) of the second phase 2; signal proportional to the current x _? (voltage _Ie ) of the third Phase 3> to the inverted signal proportional to the current ΐ, (voltage II,) of the first phase I; signal proportional to the current Χι (voltage II ₇ ) of the second phase 2, to the inverted signal proportional to the current x (voltage I ₃ ) of the third phase Z _o

The input signals of the first, second and third blocks 21 - 23 divisions are characterized by the dependences And ₂ "

ΐ'23 (Φ ^ig · 5) ^{and are} determined within the limits shown in FIG. 5 solid lines, expressions similar to (7), i.e. at the output of each of the division blocks 21 - 23, the signal changes linearly from zero to a value proportional to 1? / 3 in the corresponding sections of the change ω 1: (Fig. 5).

At the same time, at the output of the first, second, third formers 12-14 pulses Pulses of a duration in the positive half-period of current ΐ, (voltage and,) first phase 1, current ί (voltage H. ₂ ) second phase 2, current x ₃ (voltage 11 ^) the third 'phase 3, and with a pause duration in the negative half-period of these signals.

Signals 1) _n , II 11 _and from the outputs of the formers 12 to 14 pulses are inverted in the first, second and third elements of NOT 1.8 - 20, at the output of which signals are formed, respectively, and ₁₈ , and _(o , and ₂₀ (lig. 5) .. Signals II and II, ₄ from the outputs of the first

11 1486950 12

and the third formers 12 and 14 pulses arrive at the inputs of the first element 24 of the match; 11 ^, II _gv from the outputs of the first and third elements of HE 18 and 20 to the inputs of the second element 25 of coincidence; 11 _<9 , 1 ' _3o from the outputs of the first shaper 12 pulses, the second and third elements NOT 19-20 - to the inputs of the third element 26 of the match; P _ъ , 1 ' _n from the outputs of the first element HE 18, the second and third, the formers 13 and 14 pulses - to the inputs of the fourth element 27 of the match; 1 ' _n , And _<3 , 5

from the outputs of the first and second drivers 12 and 13 pulses to the inputs of the fifth element 28 matches; and _{? 9} , and _s9 from the outputs of the first and second elements NOT 18 and 19 - to the inputs of the sixth 20 element 29 matches "

As a result, at the output of each element, coincidences are formed by him (pulses each with a duration of 17/3 rad. (Fig. 5). And within each 25 period of the current change Ϊ, (voltage II,) of the first phase 1, the pulse from the output of the first coincidence element 24 takes the interval from Ce (0; 17/3]; from the output of the third coincidence element 26 — the interval ω I: e [7/3;? .k / 3]; from the output of the fifth coincidence element 28 — the interval ωΐ "[2 7/3; 11]; from the output of the second element 25 coincidence - the interval ωίε ["; 4 7/3]; from the output of the fourth element 27 matches - the interval ω ba [4 7/3;

5 7/3]; from the output of the sixth element 29 - the interval ωίε [5 K / 3; 21G]

(Fig. 5). ₄₀

The signals from the outputs of the first, second, third, fourth, fifth, sixth elements 24 - 29 coincidence, characterized by dependencies on ω £, respectively 11 ^, P ₁₅ , II,

V ^and 2 ₉ (Fig. 5), are fed to the control inputs of the first, second, third, fourth, fifth and sixth keys 38 - 43, respectively, which are closed (pass the signal from input to output) ⁵

for the duration of the corresponding pulse at the control input.

Simultaneously to the input of the first key 38 from the output of the first block 21 divisions for a period of time $ 5

OL e [0; ΙΓ / 3], when the key 38 is closed, a signal arrives and ₂₁ , which varies from zero to a value proportional to 7 / 3. -This signal from the output of the key is fed to one of the inputs of the sixth adder 44 "During the next period of time and LzeG"? / 3;

2 7/33, when the third key 40 is closed. The voltage from the output of the third element 26 matches at its control input, the signal from the output of the second adder 31 and _e) , obtained by summing the signal in it and _2g from the output of the second division unit 22 with the signal, proportional to 7/3, from the output of the block 33 of the reference voltage, through the third key 40 is also fed to o'Din from the outputs of the sixth adder 44.

Then, when changing from C from 2 7/3 to 1 ?, when the fifth key 42 is closed with voltage and from the output of the fifth element 28 coincidence at its control input, the signal from the output of the third adder 32 X1 _3g , which is obtained by summing the signal I ₂₃ from the output of the third division unit 23 with a signal proportional to 2 ^ / 3, from the output of the first large-scale amplifier 34, at the input of which is a signal from the output of the reference voltage unit 33, goes through the fifth switch 42 also to one of the inputs of the sixth adder 44.

In the next interval (4 b ets ?;

4I / 3], when the second key 39 is closed by voltage and _{? 3} - from the output of the second element 25 coincidence at its control input, the signal from the output of the first adder is 30 11 ^, which is obtained by summing the signal ϋ _5ι from the output of the first block 21 in it division with a signal proportional to 7, from the output of the second large-scale amplifier 35, at the input of which is a signal from the output unit of the reference voltage block 33, is fed through the second switch 39 also to. one of the inputs of the sixth adder 44.

During the next period of time e [4 7/3; 5 7/3], when the fourth key 41 is closed by voltage And ₅₇ s, the output of the fourth element 27 coincides at its control input, the signal II from the output of the fourth / th adder 36, which is obtained by summing the signal in it'I _3t from the output of the second adder 31 with a signal proportional to 1? from the output of the second large-scale amplifier 35, through the fourth key 41 also post 1486950 "

14

13

(Paet to one of the inputs of the sixth adder 44.

Then, PRTS change ωϋ ot5? / 3 to ^21/1 rad., When closed sixth key 43 napryazhenyem and _2E output from the sixth coincidence element 29 at its control input signal of 0 ₃₇ with the output of the fifth adder 37, the resultant summation therein signal 11 ₃₁ from the output of the third adder 32 with a signal proportional to ίίρΗΑ., from the output of the second large-scale amplifier 35, through the sixth key 43 is also fed to one of the inputs of the sixth adder 44.

As a result, at the output of the sixth adder 44, a signal 11 ^, is generated. realizes expressions (8) and (9) proportional to the instantaneous phase value of the first phase of the current ΐ, (voltage and,) and is the output signal of the unit 10 for determining the instantaneous value of the phase q>. the first phase of the current ϊ ₁ or the G1 block for determining the instantaneous phase value of the first phase of the voltage and,.

A signal from the output of block 10, proportional to the instantaneous phase ιή of the first phase of current ϊ _ι , is fed to the subtractive input of the algebraic summation unit 45, the first summing input of whichgoggle simultaneously receives a signal from the output of block 11 _{and the} first voltage phase

. Moreover, if, in accordance with (10), a zero signal is found at the second summing input of the algebraic summing unit. When the signal from the output of the comparator 47, the inputs of which are also signals from the outputs of blocks 10 and 11, closes the seventh key 46 by applying to its control input a signal from the output of the comparator .47, and to the second summing input of the block 45 algebraic summing through the key 46 from the output of the third large-scale amplifier 48, at the input of which is a signal proportional to "рад rad.", from the output of the second large-scale amplifier 35, a signal is proportional to 2? glad. in accordance with the expression (10). As a result, the output of block 45 of algebraic summation generates a signal proportional to the phase difference between the current and the voltage of a symmetric three-phase system, which is fed to the input of the recording unit 49 for its fixation.

Most of these elements (Fig. 4) are performed on the basis of chips manufactured by domestic industry. The transmission coefficients of the first 34 and the third 48 scale amplifiers are equal to two, the second scale amplifier 35 - three.

The application of the proposed method and device allows you to receive a continuous signal proportional to the instantaneous value of the difference at the appropriate time. At the same time, the device eliminates the dependence of the information received. about the phase difference from the frequency of the investigated signals, since the procedure for obtaining this information is based on a comparative analysis of the instantaneous values of the investigated signals and on the time intervals corresponding to their position.

In addition, taking into account that a comparative study of symmetric three-phase signal systems is introduced in the method and device, information on the instantaneous value of the phase difference can also be obtained in transient conditions. These circumstances allow for the expansion of the application of the proposed method for determining the phase difference and device for its implementation.

At the same time, by analyzing the information on the instantaneous value of the phase difference for the corresponding point in time, the speed and accuracy of obtaining information on the value of the phase difference at a given point in time increase, whereas in the prototype this information is the average value for the time interval corresponding to the period of the primary signal for its further information, and the process of smoothing to obtain a continuous signal implies the presence of a delay in obtaining information and reducing its accuracy.

Claims (2)

Claim 1. The method of determining the phase difference between the current and voltage of a symmetric three-phase system, 1486950 The 16 signals in that they form signals proportional to the instantaneous values of currents and voltages of all phases of the system, I form a signal proportional to the phase difference, distinguished by the fact that, in order to increase the speed of obtaining information about the instantaneous value of the phase difference, the instantaneous voltages of the first, second and third phases of the current determine the instantaneous value (^ - (b) of the first phase of the current; the instantaneous values of the first phase of the voltage are determined from the instantaneous values of the voltages of the first, second and third phases of the voltage, compared by scientists instantaneous values by subtracting the instantaneous value (/, · (£) of the first phase current of the instantaneous phase values Ιζ _{(£) of the first phase voltage, with subsequent determination of the difference and and if said negative difference then added signal thereto which is proportional to 2 /? happy, with signals proportional to the instantaneous phase value. The first phase of the current and the instantaneous phase value of the first voltage phase, with a positive instantaneous value of the current or voltage of the first phase, is formed by dividing the signal proportional to the instantaneous value to the inverted signal proportional to the instantaneous value of the current or voltage of the second phase, followed by multiplying the result of dividing by a constant factor if the sign of the instantaneous value of the current or voltage of the third phase coincides with the sign of the instantaneous value of the current or voltage of the first phase and by de '. a signal proportional to the instantaneous value of the current or voltage of the third phase, by an inverted signal proportional to the instantaneous value of the current or voltage of the first phase, followed by multiplying the result of dividing by a constant factor by adding the result of the multiplication with the signal proportional to 1? / 3 rad, if the signs of the instantaneous values of the currents, or the voltages of the second and third phases do not simultaneously coincide with the sign of the instantaneous value of the current or voltage of the first phase, and also by dividing the signal, is proportional to th instantaneous value of current or voltage of the second phase, on an inverted signal proportional to the instantaneous value of current or voltage of the third phase, and then multiplying the division result by a constant coefficient and adding the result of multiplication with a signal proportional to 2 rad _about 7/73, if the sign of the instantaneous current values or the voltage of the second phase coincides with the sign of the instantaneous value of the current or voltage of the first phase, and with a negative instantaneous value of the current or voltage of the first phase is formed similarly with itelnym summing the result with a signal proportional to d ¹ rad, the constant factor in all cases is proportional 7r / 3 rad " 2o A device for determining the phase difference between a current and a voltage of a symmetric three-phase system containing sensors for currents of all phases, sensors for voltages of all phases, a comparator, an algebraic summing unit, the output of which is connected to a recording unit ·, characterized in that, in order to increase the receiving speed information on the instantaneous value of the phase difference, - in it the introduction of a unit for determining the current value of the phase of the first current phase, connected by its first three inputs to the outputs of current sensors, and a current detection unit phase of the first phase of the voltage, connected by its first three inputs respectively to the outputs of the voltage sensors, and the fourth, fifth and sixth inputs of the blocks determining the current value of the first phase of voltage and current are connected respectively to the outputs of the additionally entered reference voltage flea, first and second large-scale amplifiers connected to their inputs as well. To the output of the reference voltage block, and the outputs of the said blocks for determining the current phase values of the first phase of the current and voltage are connected respectively -retarded with the subtractor and the first summing unit rhodami algebraic summation and the inputs of the comparator, and wherein the current value determination unit fazy.toka first phases, and the block determined. 17 1486950 18 dividing the current phase value of the first phase voltage contains three pulse shapers, the inputs of which are connected to the first three inputs of the current phase value determination units, three inverters, three division units, six coincidence elements, three NOT elements, six adders, six keys, while the inputs of the first division unit are connected to the inputs corresponding to the dividend and the divider, respectively, the input of the first pulse shaper and, through the second inverter, the input of the second pulse shaper, the inputs corresponding to the dividend and delimited the second division unit is connected respectively to the input of the third pulse shaper and through the first inverter to the input of the first pulse shaper, to the inputs corresponding to the dividend and divider, the third division unit, respectively, the input of the second pulse shaper is connected and through the third inverter the input of the third pulse shaper, outputs The first, second and third division units are connected respectively to the first inputs of the first, second and third adders, the second input of the second adder is connected to four the dry input of the current phase value detection unit, which is connected to the output of the reference voltage unit, the second input of the third adder is connected to the fifth input of the current phase value detection unit and connected to the output of the first large-scale amplifier, the second input of the first adder and the first inputs of the fourth and fifth adders are connected to the sixth input of the block determining the current phase value, which is connected to the output of the second large-scale amplifier, the second inputs of the fourth and fifth adders are connected respectively to the outputs the second and third adders, six inputs of the sixth adder through the first, second, third, fourth, fifth and sixth keys are connected respectively to the outputs of the first division unit, the first, second, fourth, third and fifth adders, and the control inputs of the first, second, third, the fourth, fifth and sixth keys are connected to the outputs of the first, second, third, fourth, fifth and sixth matches, respectively, and the output of the first pulse shaper is connected to the first inputs of the first, third, fifth, and cutting the first element NOT with the first inputs of the second, fourth and sixth elements of coincidence, the output of the second pulse shaper is connected to the second inputs of the fourth and fifth, and through the second element NOT to the second inputs of the third, sixth elements of coincidence, the output of the third driver is connected to the second input of the first and the third input of the fourth, and through the third element NOT - with the second input of the second and third input of the third match element, in addition, the seventh key is entered, and the output of the comparator is connected to the control input of the seventh Lyucha through which a second summing input of algebraic summing unit connected to the output of further scaling inputted third amplifier connected with its input with the output of the second scaling amplifier. 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