RU2093841C1 - Measuring transducer for current and voltage harmonic components - Google Patents

Abstract

FIELD: electric measurement technology. SUBSTANCE: voltage being measured is filtered off; clock pulses and measurement interval equal to fundamental period are shaped according to filtered-off signal by means of frequency multiplier 13, frequency divider 19, and write and reset pulse shapers 12 and 14, respectively; reference sine- and cosine-wave signals of same frequency as harmonic being measured are shaped by means of first and second functional transducers 6 and 7. Orthogonal components of current and voltage harmonics are measured in base of reference harmonic signals of respective frequency by digital integration of products of current and voltage derivatives by reference sine- and cosine-wave signal with aid of four reversing counters 30-33 whose content is re-entered at end of each measurement period in buffer registers 34-37 wherefrom it is entered in microcomputer 38. Current and voltage harmonics, phase shift angle between them, active, reactive, and total power are calculated by means of microcomputer. EFFECT: enlarged functional capabilities, improved accuracy in measuring fundamental component of current and voltage. 3 dwg

Description

 The invention relates to electrical engineering and is intended for use in information-measuring systems for analyzing the electromagnetic compatibility of equipment, as well as in automated systems for scientific research of electric power processes in electrical devices and complexes with semiconductor converters.

Known transducers of harmonic components of current and voltage, containing a primary voltage converter, the input of which is connected to the potential input bus of the device, a primary current converter, the input of which is connected to the current input bus of the device, a series-connected low-pass filter, a frequency multiplier and a frequency divider, filter input low frequency coupled to the primary voltage converter, the output of the frequency divider is connected to the combined inputs of the first and second T-three Gere, data inputs type functional converters | sinx | and | cosx | combined and connected to the output of the frequency multiplier, the first and second multiplication units, the first inputs of which are combined and connected to the first current converter, the second inputs are connected respectively to the outputs of the functional converters of the form _{2sinx | and | cosx |} and the outputs are connected respectively to the inputs of the first and second voltage-frequency converters of a synchronous type, the control inputs of which are combined and connected to the output of the frequency multiplier, the first, second, third and fourth two-input logic elements AND, the first inputs of the first and second two-input logic elements And are connected respectively to the direct and inverse outputs of the first T-flip-flop, and the second are combined and connected to the output of the first voltage-frequency converter of the synchronous type, the first inputs of the third and h of the fourth of the two-input logic elements AND are connected respectively to the direct and inverse outputs of the second T-flip-flop, and the second inputs are combined and connected to the output of the second voltage-frequency converter of the synchronous type, the first and second reversible counters, the summing inputs of which are connected respectively to the outputs of the first and third two-input logical elements AND, subtracting inputs are connected to the outputs of the second and fourth two-input logical elements AND, respectively, are connected in series a write pulse generator and a reset pulse generator, an input of a write pulse generator is connected to the direct output of the first T-trigger, the output of a reset pulse generator is connected to the combined R inputs of the first and second reversible counters, the first and second buffer registers, the information inputs of which are connected to the outputs, respectively the first and second reversible counters, the sync inputs are connected to the output of the recording pulse shaper, and the outputs are the outputs of the device that control the inputs of the functional converters _2sinx Type _{Developers | and | cosx |} combined and connected through a threshold element to the output of the primary voltage converter (RF patent N 1485141, 1989, class G 01 R 19/06; Aut. St. USSR N 1397843, 1986, class G 01 R 19/06).

 In such devices, the in-phase and quadrature components of the fundamental current harmonic are measured by digitally integrating the product of the measured current by the quasi-harmonic signal 2sinx | for the in-phase component and digital integration of the product of the measured current by the quasi-harmonic signal 2cosx | for the quadrature component. Moreover, averaging is performed over the period of the measured current, and the formation of reference quasiharmonic signals is performed using functional converters of the form 2sinx | and | cosx |, which are controlled by the output pulses of a threshold element connected to the primary voltage converter. In the known measuring transducer, only simultaneous measurement of the in-phase and quadrature components of the same current harmonic is carried out, the number of which is determined rigidly by the programs stored in the ROM. It is not possible to measure several current harmonics, voltage harmonics, and phase shifts of current and voltage harmonics. In addition, since the amplitudes of harmonics in power supply systems decrease with increasing frequency, the accuracy decreases when measuring higher harmonics due to an increase in the relative quantization error.

 Thus, the disadvantages of the known measuring transducers are limited functionality and low accuracy of measurement of higher harmonic components.

 Of the known devices, the closest to the achieved result to the proposed technical solution is a measuring transducer of harmonic components of current and voltage, containing a primary voltage converter, the input of which is connected to the potential input bus of the device, and the output through a series-connected low-pass filter, a frequency multiplier and a frequency divider are connected with combined inputs of the first and second T-flip-flops and control inputs of a functional converter of the form 2sinx | and a functional converter of the form 2cosx |, a primary current converter, the input of which is connected to the current input bus of the device, four multiplication units, the first inputs of the first and second of which are combined, the second inputs are connected respectively to the outputs of the functional converters of the form 2sinx | and | cosx |, and the outputs are connected to the information inputs of the first and second voltage-frequency converters, respectively, of the synchronous type, the first inputs of the third and fourth multiplication units are combined, the second inputs of the third and fourth multiplication units are connected to the outputs, respectively, of a functional converter of the form 2sinx | and a functional converter of the form 2cosx |, and the outputs are connected to the information inputs of the third and fourth voltage-frequency converters of the synchronous type, synchronizing inputs of the first, second, third and fourth voltage-frequency converters of the synchronous type and the information inputs of the functional converters of the form 2sinx | and | cosx | are combined and connected to the output of the frequency multiplier, and the outputs are connected to pairwise combined second inputs of the first and second, third and fourth, fifth and sixth, seventh and eighth two-input elements And, the first outputs of the first and fifth elements And are combined and connected to the direct output of the first T-flip-flop, whose inverse output is connected to the combined first inputs of the second and sixth AND elements, the first inputs of the third and seventh AND-elements are combined and connected to the direct output of the second T-flip-flop, whose output is connected to the combined first inputs of the fourth and eighth AND elements, the outputs of the first and second, third and fourth, fifth and sixth, seventh and eighth AND elements are connected in pairs to the summing and subtracting inputs of the first, second, third and fourth reversible counters, respectively The R-inputs of which are combined and connected to the output of the reset pulse shaper, and the outputs are connected to the information inputs of the first, second, third and fourth buffer registers, respectively, C-inputs of which combined and connected to the output of the recording pulse shaper connected between the direct output of the first T-flip-flop and the input of the reset pulse shaper, and the outputs are connected to the parallel ports of the unit for calculating the parameters of the harmonic components of voltage and current, the interrupt request for servicing the measuring transducer is connected to the output of the pulse shaper reset, the output of the primary current Converter is connected to the combined first inputs of the first and second blocks of multiplication, the output of the primary pre verters voltage is connected to the combined first inputs of the third and fourth multiplying units (patent of RF N 2003113, 1993, Cl. G 01 R 19/06).

 In the known device, the measured voltage is filtered and the filtered signal using a frequency multiplier and a frequency divider generates clock pulses and the measurement interval equal to the voltage period, and using the first and second functional converters reference sinusoidal and cosine signals synchronized with the measurement period. The measurement of the orthogonal components of the harmonics of current and voltage is carried out in the basis of reference harmonic signals by digitally integrating the products of current and voltage to the reference sinusoidal and cosine signals using four reversible counters, the contents of which are transferred to the buffer registers at the end of each measurement period, from which information is entered into the block calculating the parameters of the harmonic components of voltage and current, implemented using a microcomputer. The parameters of the voltage harmonic, in-phase and quadrature components of the current harmonic relative to the voltage harmonic, active and reactive power of the harmonic, the phase angle of the current relative to the voltage and the cosine of the phase angle are calculated using a microcomputer for each period.

где n₀ число разрядов счетчиков.In the known measuring transducer, only one current harmonic and the corresponding voltage harmonic, the number of which is determined by the programs stored in the ROM, are simultaneously measured. It is impossible to measure others, as well as several harmonics of current and voltage. In addition, since harmonic amplitudes in power supply systems usually decrease with increasing frequency (Arrilaga D. Bradley D. Vodger P. Harmonics in electrical systems / Transl. From English. M. Energoatomizdat, 1990, p. 160, Fig. 6, 25) then, when measuring the higher harmonic components, the accuracy decreases due to an increase in the relative quantization error

where n _{0 is the} number of bits of the counters.

где m номер измеряемой гармоники;
I_m величина тока m-гармоники.When measuring higher harmonics by multiplying the input signals by the reference signals of the measured frequency and averaging the products, the absolute error of the result is also Δ ₁ and the relative error is

where m is the number of the measured harmonic;
I _{m the} magnitude of the current m-harmonics.

From (1) it follows that with a decrease in the level of the investigated harmonic, the measurement error increases. For example, for n ₀ 10, the error in measuring the first harmonic
δ ₁ = 0.1%,
and the harmonic measurement error m 11, the level of which is 0.01 • I ₁ , i.e. 1% is equal
δ ₁₁ = 10%,
those. exceeds the measurement error of the fundamental harmonic by 100 times.

 Therefore, the disadvantages of the known measuring transducer of harmonic components of current and voltage are limited functionality and low accuracy of measurement of higher harmonic components.

 The purpose of the invention is the expansion of functionality and improving the accuracy of the measurement of higher harmonic components.

 This goal is achieved in that a known measuring transducer of harmonic components of current and voltage, containing a primary voltage transformer, the input of which is connected to the potential input bus of the device, and the output through a series-connected low-pass filter, a frequency multiplier and a frequency divider is connected to the combined inputs of the first and second T-flip-flops and control inputs of a functional converter of the form | sinx | and a functional converter of the form 2cosx |, a primary current converter, the input of which is connected to the current input bus of the device, four multiplication units, the first inputs of the first and second of which are combined, the second inputs are connected respectively to the outputs of the voltage-frequency functional converters of the synchronous type, the first inputs of the third and the fourth multiplication blocks are combined, the second inputs of the third and fourth multiplication blocks are connected to the outputs, respectively, of a functional converter of the form 2sinx | and functional converter type 2cosx | and the outputs are connected to the information inputs of the third and fourth voltage-frequency converters of the synchronous type, the synchronizing inputs of the first, second, third and fourth voltage-frequency converters of the synchronous type and the information inputs of the functional converters of the form 2sinx | and | cosx | combined and connected to the output of the frequency multiplier, and the outputs are connected to pairwise combined second inputs of the first and second, third and fourth, fifth and sixth, seventh and eighth two-input elements And, the first inputs of the first and fifth elements And are combined and connected to the direct output of the first T-flip-flop, whose inverse output is connected to the combined first inputs of the second and sixth AND elements, the first inputs of the third and seventh AND-elements are combined and connected to the direct output of the second T-flip-flop, inverse whose output is connected to the combined first inputs of the fourth and eighth AND elements, the outputs of the first and second, third and fourth, fifth and sixth, seventh and eighth AND elements are connected in pairs to the summing and subtracting inputs of the first, second, third and fourth reversible counters, The R-inputs of which are combined and connected to the output of the reset pulse generator, and the outputs are connected to the information inputs of the first, second, third, and fourth buffer registers, respectively, whose C-inputs are are connected and connected to the output of the recording pulse shaper connected between the direct output of the first T-trigger and the input of the reset pulse shaper, and the outputs are connected to the parallel ports of the unit for calculating the parameters of the harmonic components of voltage and current, the interrupt request for servicing the measuring transducer is connected to the output of the pulse shaper the reset, the input of which is connected to the output of the recording pulse shaper, two differentiating devices are additionally introduced, the first of which includes is connected between the output of the primary voltage converter and the combined first inputs of the third and fourth multiplication blocks, the second is connected between the output of the primary current converter and the second multiplication blocks, and the frequency multiplier is made with a controlled transmission coefficient, its control input is connected to the output of the unit for calculating the parameters of harmonic voltage components and current, the input of the recording pulse generator is connected to the output of the low-pass filter.

 In FIG. 1 shows a functional diagram of a measuring transducer of harmonic components of current and voltage.

 The device contains a primary voltage converter 1, the first 2 and second 4 differentiating devices, a primary current converter 4, a low-pass filter 5, a functional converter of the form 2sinx | 6 and functional converter type 2cosx | 7, the first 8, the second 9, the third 10 and the fourth 11 multiplication blocks, a recording pulse shaper 12, a frequency multiplier 13 with a controlled transmission coefficient, a reset pulse shaper 14, the first 15, the second 16, the third 17 and the fourth 18 synchronous voltage-frequency converters type, frequency divider 19, first 20 and second 21 T-flip-flops, first 22, second 23, third 24, fourth 25, fifth 26, sixth 27, seventh 28, eighth 29 elements And, first 30, second 31, third 32, fourth 33 reverse counters, first 34, second 35, third 36 and fourth 37 buffer register Unit calculating parameters of the harmonic components of voltage and current 38.

 In the measuring transducer of harmonic components of current and voltage, the input of the primary voltage converter 1 is connected to the input of the potential bus of the device, the input of the primary current converter 3 is connected to the input current bus of the device, the low-pass filter 5, the frequency multiplier 13 and the frequency divider 19 are connected in series, the input of the low-pass filter frequency 5 is connected to the output of the primary voltage converter 1, the output of the frequency multiplier 13 is connected to the combined information inputs of the functional converter Atelier kind 2sinx | 6 and functional converter type 2cosx | 7 and the combined clock inputs of the first 15, second 16, third 17 and fourth 18 voltage-frequency converters of the synchronous type, the output of the frequency divider 19 is connected to the combined control inputs of a functional converter of the form 2sinx | 6 and functional converter type 2cosx | 7 and the combined inputs of the first and second T-flip-flops 20 and 21, the first inputs of the first and second multiplication units are combined and connected through the second differentiating device 4 to the output of the primary current transducer 3, the second inputs are connected to the outputs of the functional converters 6 and 7, respectively, and the outputs connected to the information inputs of the first 15 and second 16 voltage-frequency converters, respectively, the first inputs of the third and fourth multiplication blocks 10 and 11 are combined and connected through the first differentiating device 2 to the output of the primary voltage converter 1, the second inputs are connected to the outputs of the functional converters 6 and 7, respectively, and the outputs are connected to the information inputs of the third 17 and fourth 18 voltage-frequency converters, respectively, the output of the first voltage-frequency converter 15 is connected to the combined second inputs the first and second two-input logic elements And 22 and 23, the first inputs of the first and fifth two-input elements And 22 and 26 are combined and connected to the direct output of the first T-trigger Era 20, and the first inputs of the second and sixth elements And 23 and 27 are combined and connected to the inverse output of the first T-trigger 18, the output of the second voltage-frequency converter 15 is connected to the combined second inputs of the third and fourth two-input logic elements And 24 and 25, the first the inputs of the third and seventh elements And 24 and 28 are combined and connected to the direct output of the second T-trigger 21, and the first inputs of the fourth and eighth elements And 25 and 29 are combined and connected to the inverse output of the second T-trigger 21, the output of the third converter voltage-frequency 17 is connected to the combined second inputs of the fifth and sixth two-input logic elements And 26 and 27, the output of the fourth voltage-frequency converter 9 is connected to the combined second inputs of the seventh and eighth two-input logic elements And 28 and 29, the outputs of the first, third, fifth and of the seventh two-input logic elements And 22, 24, 26, 28 are connected to the summing input of the first, second, third and fourth reversible counters 30-33, respectively, the outputs of the second, fourth, sixth and eighth two-input elem Comrade I, 23, 25, 27, 29 are connected to the subtracting inputs of the first, second, third and fourth reversible counters 30-33, respectively, the R-inputs of the first, second, third and fourth reversible counters 30-33 are combined and connected to the output of the reset pulse generator 14, the input of which is connected through a pulse shaper to record 12 to the output of the low-pass filter 5, the information inputs of the first 34, second 35, third 36, fourth 37 buffer registers are connected to the outputs of the first 30, second 31, third 32 and fourth 33 reverse counters, the C-inputs of the first 34, second 35, third 36, fourth 37 buffer registers are combined and connected to the output of the write pulse shaper 12, and the outputs are connected to the parallel ports of the unit for calculating the parameters of the harmonic components of the voltage and current, the interrupt request input for measuring the converter is connected to the output of the reset pulse generator 14, the control input of the frequency multiplier 13 is connected to the output of the unit for calculating the parameters of the harmonic components of the voltage and current.

 Timing diagrams illustrating the principle of operation of the measuring transducer of harmonic components of current and voltage are shown in FIG. 2, where the output signals of the elements of the device are indicated by the symbol u with an index corresponding to the number of the element in the functional diagram (Fig. 1).

где U_Mm, Φ_m- амплитуда и фаза m-й гармоники (для упрощения анализа примем Φ₁=0
ω - частота;
m номер гармоники,
поступает на вход первичного преобразователя 1 напряжения, а с его выхода подается на фильтр нижних частот 5, который подавляет высшие гармоники напряжения и формирует сигнал
u₅= U_мsin(ωt+θ),
где U_M амплитуда гармонического сигнала на выходе фильтра нижних частот 5,
θ - фазовый сдвиг сигнала фильтра нижних частот 5 относительно первой гармоники напряжения u, вносимый фильтром 5.A measuring transducer of harmonic components of current and voltage works as follows. Non-sinusoidal supply voltage

where U _Mm , Φ _m is the amplitude and phase of the mth harmonic (to simplify the analysis, we take Φ ₁ = 0
ω is the frequency;
m is the harmonic number,
enters the input of the primary voltage converter 1, and from its output is fed to a low-pass filter 5, which suppresses the higher harmonics of the voltage and generates a signal
u ₅ = U _m sin (ωt + θ),
where U _{M the} amplitude of the harmonic signal at the output of the low-pass filter 5,
θ is the phase shift of the signal of the low-pass filter 5 relative to the first harmonic of the voltage u introduced by the filter 5.

где k₂ коэффициент передачи дифференцирующего устройства 2.The voltage u ₁ from the output of the primary Converter 1 is supplied to the input of the first differentiating device 2, the output of which is a signal

where k ₂ the transmission coefficient of the differentiating device 2.

где I_Mm амплитуда m-й гармоники тока;
ψ_m - фазовый сдвиг,
преобразуется первичным преобразователем тока 3 в напряжение
u₃ K₃i,
где k₃ коэффициент передачи первичного преобразователя тока 3.Measured non-sinusoidal current

where I _{Mm is the} amplitude of the mth current harmonic;
ψ _m is the phase shift,
converted by a primary current transformer 3 to voltage
u ₃ K ₃ i,
where k _{3 is} the transmission coefficient of the primary current transducer 3.

где k₄ коэффициент передачи второго дифференцирующего устройства.The signal u _{3 is} converted by the second differentiating device 4 into voltage

where k _{4 is} the transmission coefficient of the second differentiating device.

The code from one of the ports of the unit for calculating the parameters of harmonic components of voltage and current 38 acts on the control input of the frequency multiplier 13, as a result of which its transmission coefficient is set equal to
k ₁₃ m • n,
where n is the coefficient.

The signal from the output of the low-pass filter 5 is fed to the input of the frequency multiplier 13 by m • n, the output of which is generated by pulses u ₁₃ with a frequency proportional to the frequency f of the supply network and the number m of the measured harmonic
f ₁₃ mnf mn / T
where T 1 / f network period.

The pulses u ₁₃ from the output of the frequency multiplier 13 are supplied to the frequency divider 19 by n / 2, the output of which is formed by the pulses u ₁₉ with a frequency f ₁₉ 2mf ₁₃ / n, which is equal to twice the frequency of the measured harmonic. The pulses u ₁₉ arrive simultaneously at the input of the T-flip-flop 20 with the installation on the positive edge and the T-flip-flop 21 with the installation on the negative edge. As a result, at the output of the first T-flip-flop 20, a pulse train u ₂₀ is formed having a frequency of the measured harmonic, but shifted in phase relative to the corresponding voltage harmonic by an angle γ _m (see Fig. 3). At the output of the second T-flip-flop 21, a pulse sequence acts in phase relative to the pulse sequence u ₂₀ by a quarter of the period, and relative to the voltage harmonic by an angle (90 + γ _m ) el. hail.

The signal u ₅ from the output of the low-pass filter 5 is fed to the input of the write pulse shaper 12, the output of which is connected to the input of the reset pulse shaper 14. At the beginning of each measurement period, the pulses u ₁₂ and u ₁₄ act on the outputs of these shapers, which control the recording of information in the buffer registers 34-37 and the installation of the initial state of the reverse counters 30-33. The pulse u ₁₄ signals the completion of the measurement cycle for the unit for calculating the harmonic components of voltage and current 38, after which it is possible to read information in 38 from the buffer registers 34 37.

где U_a амплитудное значение сигналов.Functional converters 6 and 7 are digital shapers of the reference quasi-harmonic signals | sinx | and | cosx | Their work is as follows. At times corresponding to the positive and negative edges of the pulses u ₁₉ , the functional converters are installed by the output signal u _{19 of} the frequency divider 19 to the initial state. Next, the functional converters 6 and 7 convert the number of pulses u ₁₃ received from the output of the frequency multiplier 17 to their information inputs into quasi-harmonic signals

where U _{a is the} amplitude value of the signals.

образуют базис ортогональных функций, в котором осуществляется измерение составляющих m-ых гармоник напряжения и тока.Quasi-harmonic signals

form the basis of orthogonal functions, in which the components of the mth harmonics of voltage and current are measured.

векторы m-ых гармоник напряжения и тока, сдвинутые по фазе друг относительно друга на угол Φ_m-ψ_m

векторы опорных напряжений, образующие ортогональный базис для m-ых гармоник тока и напряжения;

векторы m-ых гармоник напряжения и тока, формируемых на выходах соответственно первого 2 и второго 4 дифференцирующих устройств;
U $\genfrac{}{}{0ex}{}{\text{(2)}}{\text{mn}}$ , U $\genfrac{}{}{0ex}{}{\text{(2)*}}{\text{mn}}$ , I $\genfrac{}{}{0ex}{}{\text{(4)}}{\text{mn}}$ , I $\genfrac{}{}{0ex}{}{\text{(4)*}}{\text{mn}}$ - проекции векторов производных m-ых гармоник напряжения и тока на оси ортогонального базиса.A vector diagram of voltages and currents explaining the operation of the transmitter is shown in FIG. 3, where indicated:

vectors of m-th harmonics of voltage and current, phase-shifted relative to each other by an angle Φ _m -ψ _m

reference voltage vectors forming an orthogonal basis for the mth harmonics of current and voltage;

vectors of m-th harmonics of voltage and current generated at the outputs of the first 2 and second 4 differentiating devices, respectively;
U $\genfrac{}{}{0ex}{}{\text{(2)}}{\text{mn}}$ , U $\genfrac{}{}{0ex}{}{\text{(2) *}}{\text{mn}}$ , I $\genfrac{}{}{0ex}{}{\text{(4)}}{\text{mn}}$ , I $\genfrac{}{}{0ex}{}{\text{(4)*}}{\text{mn}}$ - projections of the vectors of derivatives of the mth harmonics of voltage and current on the axis of the orthogonal basis.

где k₈ коэффициент передачи первого блока перемножения 8.The projection of the derivative of the mth harmonic of the non-sinusoidal current onto the sinx axis of the orthogonal basis (u ₆ , u ₇ ) is extracted as follows. The first multiplication unit 8 multiplies the signal u ₄ , which is proportional to the derivative of the current, by the reference quasiharmonic signal u ₆ . As a result, a voltage is generated at the output of the multiplication unit 8

where k _{8 is} the transmission coefficient of the first multiplication block 8.

где k₁₅ коэффициент передачи первого преобразователя напряжение-частота 15;
U_см напряжение смещения преобразователя напряжение-частота 15.The signal u _{8 is} fed to the input of the first voltage-frequency converter 15 and is converted by it into pulses u ₁₅ following with a frequency

where k ₁₅ the transmission coefficient of the first voltage-frequency Converter 15;
U _cm bias voltage converter voltage-frequency 15.

где k_п.T 0,5 k₃k₄k₈k₁₅nU_a - коэффициент передачи измерительного преобразователя для проекции произведений m-й гармоники, тока на ось sinx базиса (u₆, u₇).The output pulses of the first voltage-frequency converter 15 are supplied to the second inputs of the first and second logic elements And 22 and 23, the first inputs of which are connected respectively to the direct and inverse outputs of the first T-flip-flop 20, and the outputs are connected to the summing and subtracting inputs of the first reversible counter 30 . At the beginning of each measurement period (time t ₀ ), the first reversible counter 30 with the output pulse of the reset pulse generator 14 is set to the zero state N ₃₀ 0. Further, the pulses u ₁₅ depending on the state of the triggers Hera 20 are fed to the summing and subtracting inputs of the first reversible counter. Moreover, in time intervals of duration
τ = T / 2m,
at which sin (mωt + γ _m )> 0, the pulses U ₁₅ arrive at the summing input of the counter 30, and in m time intervals corresponding to the values sin (mωt + γ _m ) <0, these pulses are fed to the subtracting input of the counter 30. Due to this firstly, the digital integration of the product of the signal u ₄ by sin (mωt + γ _m ) is provided using the simplified unipolar functional converter 7: u ₇ = U _a | sin (mωt + γ _m ) |, and secondly, compensation U bias _cm-frequency voltage converter 15, which is necessary for operating the inverter 15 in a bipolar odnym signal. As a result, at the end of the measurement period equal to the fundamental harmonic period T, the number is written in the binary additional code in the first reverse counter

where k _{p T} 0.5 k ₃ k ₄ k ₈ k ₁₅ nU _a is the transmittance of the measuring transducer for the projection of the products of the mth harmonic, the current on the sinx axis of the basis (u ₆ , u ₇ ).

The sign of the number N ₃₀ is determined by the value of the highest digit of the binary reversible counter 30. A positive value of N ₃₀ corresponds to 0 in the highest digit, and a negative value of 1.

где k₉ коэффициент передачи второго блока перемножения 9.The projection of the derivative of the mth harmonic of the current on the cosx axis of the orthogonal basis (u ₆ , u ₇ ) is distinguished in a similar way. The second unit of multiplication 9 performs the multiplication of the signal u ₄ by the reference quasi-harmonic signal u ₇ . As a result, a signal is generated at the output of the multiplication unit 9

where k _{9 is} the transmission coefficient of the second block of multiplication 9.

где k₁₆ коэффициент передачи второго преобразователя напряжение-частота 16.The signal u ₉ enters the input of the second voltage-frequency converter 16 and is converted by it into pulses u ₁₆ following with a frequency

where k _{16 is} the transmission coefficient of the second voltage-frequency converter 16.

где k*_п.Т= 0,5k₃k₄k₉k₁₆nU_a - коэффициент передачи измерительного преобразователя для проекции производной m-й гармоники тока на ось cosx базиса (u₆, u₇).The output pulses of the second voltage-frequency converter 16 are supplied through the logic elements AND 24 and 25, respectively, to the summing and subtracting inputs of the second reversible counter 31. This counter is set at the beginning of each measurement period (time t ₀ ) to zero, and at the end of the measurement period ( moment t ₀ + T) in it in the binary-additional code the number is written

where k * _p . _T = 0.5k ₃ k ₄ k ₉ k ₁₆ nU _a is the transmittance of the measuring transducer for the projection of the derivative of the mth harmonic of the current on the axis of the cosx basis (u ₆ , u ₇ ).

где k_п.н 0,5 k₁k₂k₁₁k₁₆nU_a,
k $\genfrac{}{}{0ex}{}{\text{*}}{\text{п.н.}}$ 0,5 k₁k₂k₁₁k₁₈nU_a коэффициенты передачи измерительного преобразователя для проекций m-й гармоники напряжения на оси sinx и cosx ортогонального базиса (u₆, u₇).The projections of the mth voltage harmonic on the axis of the basis (u ₆ , u ₇ ) are extracted in a similar way using the third 10 and fourth 11 multiplication blocks, the third 17 and fourth 18 voltage-frequency converters, fifth 26, sixth 27, seventh 28 and eighth 29 elements And, the third 32 and fourth 33 reverse counters. In accordance with the logic of the device at the end of the measurement period in the third and fourth reversible counters 32 and 33 are recorded numbers, respectively

where k _bp 0.5 k ₁ k ₂ k ₁₁ k ₁₆ nU _a ,
k $\genfrac{}{}{0ex}{}{\text{*}}{\text{bp}}$ 0.5 k ₁ k ₂ k ₁₁ k ₁₈ nU _a the transmission coefficients of the measuring transducer for the projections of the mth voltage harmonic on the sinx axis and cosx of the orthogonal basis (u ₆ , u ₇ ).

At the end of each measurement period (moment t ₀ + T), the output pulse of the write pulse generator 12 records the contents of the reverse counters 30-31 in the buffer registers 34 - 37. Then, the output pulse of the reset pulse generator 14 sets the reverse counters 30- to zero state 33. The process is then repeated. At the same time, over the next measurement period, the numbers N ₃₄ N ₃₀ , N ₃₅ N ₃₁ , N ₃₆ N ₃₂ , N ₃₇ N ₃₃ are stored in the buffer registers 34-37.

действующие значения m-ых гармоник напряжения и тока

угол сдвига фаз между m-ми гармониками напряжения и тока
β_m=Φ_m-ψ_m=arctg(N₃₇/N₃₆)-arctg(N₃₅/N₃₄);
амплитудное и действующее значения синфазной составляющей m-й гармоники тока

амплитудное и действующее значения квадратурной составляющей m-й гармоники тока

активная мощность m-й гармоники
P_m=U_mI_mcosβ_m;
реактивная мощность m-й гармоники
Q_m=U_mI_msinβ_m;
полная мощность m-й гармоники
S_m=U_mI_m
Результаты вычислений выводятся на дисплей или алфавитно-цифровое печатающее устройство.According to the signal from the output of the reset pulse generator 14 to the input INT of the block for calculating the parameters of the harmonic components of voltage and current 38 (input of the interrupt request for servicing the measuring transducer), the microcomputer 38 calls the subprogram that reads the codes from the buffer registers 34-37 . Next, the parameters of the m-th harmonics of non-sinusoidal voltage and current are calculated according to the following formulas:
amplitude values of the m-th harmonics of voltage and current

effective values of m-th harmonics of voltage and current

phase angle between m voltage and current harmonics
β _m = Φ _m -ψ _m = arctan (N ₃₇ / N ₃₆ ) -arctg (N ₃₅ / N ₃₄ );
amplitude and current values of the in-phase component of the m-th harmonic of the current

amplitude and current values of the quadrature component of the m-th current harmonic

mth harmonic active power
P _m = U _m I _m cosβ _m ;
mth harmonic reactive power
Q _m = U _m I _m sinβ _m ;
mth harmonic apparent power
S _m = U _m I _m
The results of the calculations are displayed or alphanumeric printing device.

 To measure the parameters of another harmonic at the output of the block for calculating the parameters of the harmonic components of the voltage and current, it generates a code that sets a new value for the transmission coefficient of the frequency multiplier 13. The measurement procedure is similar to that considered.

т. е. в m раз меньше, чем δ_m, определяемое выражением (1). Например, при измерении 11-й гармоники, уровень которой составляет 1% от основной, относительная погрешность

т.е. на порядок меньше, чем в известном устройстве.Thus, the measurement of the parameters of harmonics of current and voltage in the proposed device is carried out by decomposing the derivatives of current and voltage into orthogonal components in the basis of reference harmonic signals (sinx, cosx) with the subsequent calculation of all parameters using the unit for calculating the parameters of harmonic components of voltage and current from the measured values components. Differentiation of signals proportional to current and voltage provides amplification of higher harmonics while maintaining (or decreasing) the level of the fundamental harmonic. Since the proposed device performs analog-to-digital conversion of derivatives of harmonics, the quantization error when measuring the m-th harmonic is

i.e., m times smaller than δ _m defined by expression (1). For example, when measuring the 11th harmonic, the level of which is 1% of the fundamental, the relative error

those. an order of magnitude less than in the known device.

 Moreover, the proposed technical solution allows you to measure both the main and higher harmonics of current and voltage, as well as perform sequentially in time measurements of different harmonics according to the program using a microcomputer. Therefore, the device has enhanced functionality.

Other important advantages of the transmitter are:
the invariance of the measurement results with respect to changes in the frequency of the supply network, which follows from equations (2) - (5);
high speed, measurement time is equal to the period of the supply voltage;
presentation of data in digital code and data processing using microcomputers.

 Using the proposed measuring transducer of harmonic components of current and voltage in electrical devices and energy systems will improve the accuracy of electricity metering and the quality of the functioning of automatic systems for regulating the operating modes of electrical equipment.

Claims (1)

 A measuring transducer of harmonic components of current and voltage, comprising a primary voltage transformer, the input of which is connected to the potential input bus of the converter, the output through a series-connected low-pass filter, a frequency multiplier and a frequency divider is connected to the combined inputs of the first and second T-flip-flops and the control inputs of the functional converter of the form | sinx | and a converter of the form 2cosx |, a primary current converter, the input of which is connected to the current input bus of the converter, four multiplication units, the first inputs of the first and second of which are combined, the second inputs are connected respectively to the outputs of the functional converters of the form | sinx | and 2cosx |, and the outputs are connected to the information inputs of the first and second voltage converters, respectively, the frequency is synchronous type, the first inputs of the third and fourth multiplication units are combined, the second inputs are connected to the outputs of respectively a functional converter of the form | sinx | and a functional converter of the form 2cosx |, and the outputs are connected to the information inputs of the third and fourth voltage converters, respectively, of the synchronous type frequency, the synchronizing inputs of the first fourth voltage converters of the synchronous type and the information inputs of the functional converters of the form | sinx | and | cosx | combined and connected to the output of the frequency multiplier, and the outputs to the pairwise combined second inputs of the first and second, third and fourth, fifth and sixth, seventh and eighth two-input elements And, the first inputs of the first and fifth elements And are combined and connected to the direct output of the first T -trigger, the inverse output of which is connected to the combined first inputs of the second and sixth elements AND, the first inputs of the third and seventh elements AND are combined and connected to the direct output of the second T-trigger, inverse output it is connected to the combined first inputs of the fourth and eighth elements AND, the outputs of the first and second, third and fourth, fifth and sixth, seventh and eighth elements AND are connected in pairs to the summing and subtracting inputs of the first fourth reverse counters, respectively, whose R inputs are combined and connected to the output of the reset pulse shaper, and the outputs are connected to the information inputs of the first fourth buffer registers, respectively, the C-inputs of which are combined and connected to the output of the pulse shaper recording pulses, and outputs to the parallel ports of the unit for calculating the parameters of the harmonic components of voltage and current, the interrupt request for servicing the measuring transducer is connected to the output of the reset pulse shaper, the input of which is connected to the output of the recording pulse shaper, characterized in that two differentiating devices, the first of which is connected between the output of the primary voltage converter and the combined first inputs of the third and fourth blocks multiplication, the second is connected between the output of the primary current transducer and the combined first inputs of the first and second multiplication units, and the frequency multiplier is made with a controlled transfer coefficient, its control input is connected to the output of the unit for calculating the parameters of harmonic voltage and current components, the input of the recording pulse generator is connected to the output low pass filter.

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