JPS5988657A - Method and device for determining quality index of electric energy in three-phase power supply net - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measuring device, in particular to a method for determining the quality index of electrical energy in a three-phase power supply network, and to a device implementing this method.

The invention can be used in special measuring and information devices or combined multifunctional devices for measuring measurement parameters of polyphase power supply networks, in particular for measuring the quality index of electrical energy in three-phase power supply networks. . This is particularly advantageous in the case of measuring devices which include very small data processing devices such as computers.

Current technological advances are characterized by energy-intensive production processes, and of the various forms of energy currently available, electrical energy is the most prominent form. The advantages of electrical energy over other forms of energy are quite obvious given its convenient transmission and use, ability to concentrate energy in a relatively small volume, and flexibility of use. be. Electrical energy, like other products, is characterized by its quality. The quality index of electrical energy is frequency deviation, voltage fluctuation, magnitude of frequency deviation, voltage peak-to-peak value, voltage asymmetry rate and unbalance rate, and distortion rate of its sinusoidal waveform.

The problem of improving energy quality is directly related to the problem of controlling the individual indices of energy quality and measuring the values of these indices. This is because only the value of the energy quality index can be used as the information necessary to implement measures taken with the aim of improving the quality of electrical energy.

Today, among the seven types of electrical energy quality indexes, voltage fluctuation V, peak voltage cobeak value, asymmetry rate ε2, and unbalance rate ε are used. It should be noted that the four types of electrical energy quality indexes are determined from the positive phase, negative phase and zero phase voltage symmetrical components, respectively denoted by the symbols U: T Uz t U:. The complex value of those 11C piezosymmetric components is expressed by the complex value of the phase voltage (T″T, 0.fi) as follows.

”='3(UA+nihejuni2T11C)・Oshi 1・
-2・-・U2='a (T-J7V+ a UB+ &Uc
)Uo=,,,(tJ, +UB+Uo)Here,
=, j2''/3 is a rotation operator.

In this case, the voltage fluctuation V in the three-phase power supply network,
It is expressed by an asymmetry rate ε2 and an unbalance rate 6°. Here, the value is the nominal voltage value in the three-phase power supply network.

The characteristic of measuring the quality index of electrical energy is that the value of these indexes is one or two orders of magnitude smaller than the non-informative parameter, which is the positive sequence voltage of the fundamental frequency, and its value is equal to the nominal value. Hereinafter, the terms "informational ξ-parameter" and "non-informative ξ-parameter" will be used to mean measured parameters and unmeasured ξ-parameters, respectively.

According to traditional standards and standard-setting documents, the value of the quality index of electrical energy should not exceed 2-5 cm, so the absolute error of the measured value should be 0.05 than the relative error should not exceed 5%. -0.1%.

Conventional methods for determining the quality index of electrical energy from voltage symmetrical component values in polyphase power supply networks, especially in three-phase power supply networks, have very low accuracy. The absolute error in measuring the quality index using equipment implementing these methods is generally between 0.5 and 2 inches, and these errors result from measurement errors of voltage symmetrical components.

Methods for determining the quality index of electrical energy are known which are based on measuring the voltage symmetrical components in a three-phase power supply network using symmetrical component filters. In these filters, the phase voltages are phase-shifted and summed by a phase-shifting circuit so as to carry out the transformation necessary for measuring voltage symmetrical components (DE 124 152).
(See No. 4).

A disadvantage of this method and the apparatus implementing it is that the circuit element actance is frequency dependent. Other measurement errors therefore occur if the frequency of the power supply network differs from its nominal value.

A device is known for carrying out the method, comprising measuring instruments for measuring the voltage symmetry and components of the positive and negative phases in a three-phase power supply network, the output terminals of these measuring instruments being combined ( (see USSR Inventor's Certificate No. 517806). The output terminals of these measuring instruments are also the input terminals of the device. The device also includes a divider, the input terminal of which is connected to the output terminal of the measuring device measuring the voltage symmetrical component.

The output signals of these meters represent the quality index of the electrical energy. The output terminal of the symmetrical component measuring device and the output terminal of the divider are connected to the recorder via a switching device. Each symmetrical component measuring device includes a series circuit consisting of an input device, a symmetrical component filter, a bandpass filter, a rectifier circuit, and a subtraction circuit, and one output terminal of the subtracting circuit is the output terminal of the corresponding symmetrical component measuring device. the other output terminal of the subtraction circuit is connected to the output terminal of the input device via a frequency deviation transducer.

However, in this device, since the circuit elements of the symmetric component filter are unstable with respect to temperature and time, the transfer coefficient does not become zero in the case of non-informative parameters (not measured). This results in a measurement error having a value equal to the sum of the products of the transfer coefficients for the non-informative nomurameters and the values of their nomurameters in the three-phase power supply network. In this case, the value of the positive sequence voltage is one or two orders of magnitude larger than the direct value of the negative phase and zero phase symmetric components used to determine the voltage asymmetry rate and voltage unbalance rate in the three-phase power supply network. Therefore, the influence of the positive sequence voltage is the most significant. Therefore, it is not possible to improve the measurement accuracy of the quality index of electrical energy, and the lower part of the operating range of the measured value is limited.

The present invention provides three-phase The object is to obtain a method and a device for determining the quality index of electrical energy in a power supply network.

The purpose is to determine the symmetrical portion of the three-phase power supply network with the magnitude used to determine the value of the quality index of electrical energy.Determine the quality index of electrical energy in the three-phase power supply network The method comprises: first determining the amplitude and first phase of a reference voltage; and then forming a positive symmetric three-phase voltage reference system, the first phase and amplitude of the reference system being equal to the first phase of the reference voltage. is equal to the previously determined value of and amplitude, and the frequency of the same reference system is equal to the frequency of the three-phase power supply network, such that the symmetrical component is determined from the difference between the output voltage and the reference voltage. This is achieved by a method for determining the quality index of electrical energy in a three-phase power supply network, in which a reference voltage is subtracted phase by phase from the input voltage.

By subtracting a reference system with the amplitude and initial phase of the above values for each phase from the input voltage, it is possible to eliminate the effects of non-informative ξ parameters, thereby reducing measurement errors and limiting the operating range of the measurement. Can be expanded.

According to one variant of the method of the invention, the amplitude and initial phase of the reference voltage are determined by measuring the amplitude and initial phase of the positive sequence voltage in said three-phase power supply network.

Such a modification of the method of the invention allows the measurement accuracy to be maximized. The reason is that the influence of the positive sequence voltage on the measurement results when measuring other quality indicators of electrical energy is completely eliminated. In this case, the measurement error depends only on the relative error of the transmission coefficient of the device with respect to the information parameter, ie the parameter being measured.

[7Thus, although there are many components of measurement error, the measurement error does not limit the lower part of the range of measured values.

This variant of the method according to the invention can be used most advantageously for measuring the quality index of electrical energy in power supply networks with low asymmetry and low neutral shift.

According to another variant of the method of the invention, it is assumed that the amplitude of the voltage reference system is equal to the voltage nominal value of the three-phase power supply network, and determining the first phase of the positive sequence voltage in said power supply network. The first phase is determined by

This modification makes the measurement process somewhat easier due to the fact that the amplitude of the reference voltage can be determined from a previously calculated value without further measurements. Another advantage of this variation is that the positive sequence voltage resulting from the difference between the input voltage and the reference voltage is directly proportional to the voltage variation and can be used to measure the peak niveak value of the voltage. In this case, the measurement accuracy of those parameters is considerably improved.

determining the amplitude of the voltage reference system by measuring the amplitude of the positive sequence voltage in said three-phase power supply network; A modification example in which the determination is made by doing the following is also possible.

This modification of the method according to the invention simplifies the measurement process, since the first phase of a phase voltage can be easily determined at the time when the instantaneous value of the corresponding phase voltage crosses the zero level.

The object of the invention is a device for determining the quality index of electrical energy implementing the method according to the invention, which comprises a measuring device for measuring three-phase voltage symmetrical components, several output terminals of this measuring device. is an output terminal of the device, and the output signal of the measuring device represents information about the value of the quality index of electrical energy. a three-phase signal generator and a forming circuit, a first input terminal of the summing circuit serving as an input terminal of the device, and an output terminal of the summing circuit measuring a three-phase voltage symmetric component; the output terminal of the controlled three-phase signal generator is connected to the other input terminal of the summing circuit, and the control input terminal of the controlled three-phase signal generator is electrically connected to the corresponding input terminal of the three-phase voltage connected to an output terminal of said measuring instrument for measuring a symmetrical component, an output terminal of said forming circuit connected to a synchronous input terminal of a three-phase signal generator, and an input terminal of said forming circuit connected to one input terminal of said device. It is also achieved by a device that determines the quality index of the electrical energy connected.

This device has a wide range of functional applications and
It can be used to measure all quality indices of r-.

Furthermore, since the amplitude is determined from the output signal of the measuring device measuring the three-phase voltage symmetrical components, the device of the invention does not require a separate measuring device for measuring the reference voltage. Further, by using the measuring device that measures the positive sequence voltage as a zero indicator of the positive sequence voltage in the output signal of the subtraction circuit,
Measurement accuracy can be further increased.

According to one variant of the device according to the invention, the controlled three-phase signal generator comprises three digital-to-analog converters, a fourth digital-to-analog converter, a register, a constant former and a counter. and a frequency multiplier, the output terminals of the three digital-to-analog converters are the output terminals of a controlled three-phase signal generator, and the output terminals of the fourth digital-to-analog converter are the output terminals of the three digital-to-analog converters. - connected to an analog input terminal of an analog converter, the input terminal of said register being a control input terminal of a controlled three-phase signal generator;
The output terminal of the register is connected to the input terminal of a fourth digital-to-analog converter, and the output terminal of the constant former is connected to the input terminal of the fourth digital-to-analog converter.
．． Second. a third converter; an output terminal of the counter is connected to an input terminal of a constant generator; an input terminal of the frequency multiplier is combined with a synchronous reset input terminal; and a control three-phase signal generator. This is the synchronous input terminal of the device.

By configuring the three-phase signal generator in this way, the response speed can be maximized since the three-phase signal generator does not contain any inertial elements, and the highest accuracy can be obtained, which depends on the accuracy of the digital-to-analog converter. can. It is a great advantage of this variant of the device according to the invention that it is possible to directly control the output code of the measuring device measuring the voltage symmetrical component in the three-phase power supply network.

In another variant of the invention, the controlled three-phase signal generator further comprises a second register, the input of which is connected to the control input of the controlled three-phase signal generator.

By so configuring the three-phase signal generator,
It is possible to completely compensate the positive sequence voltage at the input terminal of a measuring instrument that measures three-phase voltage symmetrical components, thereby increasing the measurement accuracy of the quality index of electrical energy.

The object of the invention is a device for determining the quality index of electrical energy implementing the method of the invention, comprising measuring instruments for measuring the three-phase voltage symmetrical components, the number of these measuring instruments depending on the quality to be measured. The output terminal of the measuring instrument measuring the voltage symmetrical component equal to the number of indices is the output terminal of the device, and the output signal of the measuring instrument is representative of information about the quality index of the electrical energy. The apparatus for determining the quality index further includes three subtraction circuits and a three-phase filter for symmetrical components of the positive-sequence voltage, and each output terminal of the subtraction circuit corresponds to a corresponding measuring device for measuring the symmetrical components of the three-phase voltage. the input terminal of the three-phase filter is coupled to the corresponding non-inverting input terminal of the subtraction circuit, and the output terminal of said three-phase filter is connected to the inverting input terminal of the corresponding subtraction circuit. It is also achieved by a device for determining the quality index.

This device has a simple structure, and can measure the positive-sequence voltage and the three-phase positive-sequence reference voltage with one device, that is, the three-phase filter with symmetrical components.

The method according to the invention for determining the electrical quality index in a three-phase power supply network is based on measuring a voltage symmetrical component in said three-phase power supply network, the measured value of which is the value of the electrical energy. Used to determine quality index. This method comprises the steps of determining the interpupillary distance and initial phase of a reference voltage, and forming a symmetric three-phase system of positive-sequence voltages, the initial phase and amplitude of which were previously measured. The frequency of the symmetric three-phase system corresponds to the frequency of the three-phase power supply network.

Then, the reference voltage is subtracted from the input terminal, and from the resulting difference a symmetrical component is selected that represents the quality index of the electrical energy.

It is well known that the symmetrical component of a three-phase voltage system is calculated from the following equation.

Ebi - Blue (He19a+Uca) Cod 4-1 TITA-1-Rijushun) (1) OF bow (TI
TA+ → Mr.-) Complex value of phase voltage symmetrical component, rotation - IJc complex value of phase voltage, a=e""/3 is a rotation operator.

Hereinafter, the present invention will be described in detail with reference to the drawings.

The nature of the invention is clear from the voltage waveform diagram shown in FIG. Symmetrical three-phase system UA□, UB□ with positive phase reference voltage
After the l UCl has been formed, a reference voltage is subtracted phase by phase from the input voltage platform of the three-phase power supply network Un+ Uc. The symmetrical component is selected from the thus obtained difference in their voltages.

The result of measuring X8 of the Sth (S=1.2.3) is
All symmetrical components present in a given power supply network can be expressed in the form of a linear combination.

Here, tJ7vs is the complex value of the th phase, and ko is the transfer coefficient of the measuring device for the ith phase.

In the measurement of the Sth phase, the information ξ parameter, i.e. the nominal value d of the transfer coefficient for the Sth phase to be measured
1, and the nominal value of the transfer coefficient for non-informative parameters, ie, symmetrical components that are rarely measured, is zero.

The real values of these coefficients are different from the nominal values and are expressed by the following equation.

Here, Tong is the absolute value of the deviation of the transfer coefficient from the nominal value.

If there is an error in the transfer coefficient, an error will occur in the measurement of the voltage symmetrical component. In that case, the absolute measurement error is expressed by the following equation, and the relative error is expressed by .

It is clear from the last equation that if the coefficient of the Sth phase is much smaller than the coefficient of any other phase, a modest error, δ, can result in a large error in the measurement of the Sth phase. .

Since the value of the positive-sequence voltage U is one or two orders of magnitude larger than the value of the negative-phase or zero-sequence voltage, the positive-sequence voltage is most affected by the transfer coefficient error. So, for example,
In the measurement of the quality index, the error value δ1 constituting 0.05% becomes the absolute error constituting 0.596. Therefore, the lower limit of the measured value is 1-2%, and the relative error when measuring the quality index in the range of 1-5 is 10-50%.
make up %.

According to the method of the invention, a three-phase system of reference voltages is formed 2 whose instantaneous values are as follows:

UA 1 20M181 n(t + q 1) where UMI +ψ1 are the amplitude and initial phase of the voltage reference system.

The instantaneous value of the reference value corresponds to a complex value. It is expressed by the following formula.

Since those reference voltages form a symmetric three-phase system, the symmetric components of the symmetric three-phase system are:

U-00 After performing the subtraction for each phase, the difference voltage is obtained.

ΔUA-UA-U.

ΔtrB=TJB−UB, (9) ΔUC=UC′CI where UA + Un + UC is the instantaneous value of the phase voltage.

The complex value of those voltages also corresponds to the differential voltage.

ΔUA=UA−UA□ ΔOB−匈−tJB100) ΔUo=U, −Ucm The symmetrical components of the voltage complex value according to the equation (], ) are as follows.

ΔU=U−U 111.1 ΔU2=U2 (If)
ΔU3 = U3 As seen from the last equation, only the positive phase symmetry component is subtracted, while the antiphase and zero phase symmetry components are invariant and can be determined by any known method.

The positive and negative phase symmetrical components can be used as an asymmetry factor of 6° and an unbalance factor of 6 to calculate their electrical engineering coefficients ψ−. Their values '2' and 0 are as follows.

e2-Δ■Sakura/UN, #o=ΔU:/UN here, UN
is the nominal value of the voltage in a three-phase power supply network.

Similarly, in measuring the symmetrical component of the harmonics, said component remains unchanged even after the reference voltage is subtracted from the input voltage.

In the following it will be explained how the method of the invention can be used to improve the measurement accuracy of voltage symmetrical components and therefore of the quality index of electrical energy.

So that the positive-sequence voltage coefficient ΔUW is much smaller than the
The amplitude and initial phase of the voltage reference frame are set. This can be done by controlling the values of the positive sequence voltages at voltages ΔIJA, ΔUB, ΔUo and by alternately adjusting the first phase ψ of the voltage reference system and the quadruple width TJM1 until the minimum value ΔUT is obtained. . In this case, the influence of the transmission coefficient of the device on the positive sequence voltage is such that the voltage ΔU\ is much smaller than the normal voltage uW of the three-phase power supply network. For example, δ
1=0.5% and ΔUj=0. IU'', the absolute measurement error component resulting from the influence of the positive-sequence voltage is only 0.05 cm. To this end, the quality index of the electrical energy is changed starting from the level of the 0.1 factor to the sail 2 factor. Measurements can be made down to rails.

Therefore, the influence of unmeasured /e parameters on the measurement results is reduced, so that measurement accuracy can be increased and the measurement range can be expanded.

The method of the invention for determining the quality factor of electrical energy can be carried out with the apparatus shown in FIG.

The device comprises a unit 1 for compensating the positive sequence voltage and a measuring device 2 connected via this unit 1 to input lines A, B, C. Unit 1 includes subtraction circuits 3, 4.5.

The non-inverting input terminals of these circuits are the input terminals of unit 1, and the output terminals of these circuits are the output terminals of unit 1. The output terminal of the three-phase control signal generator 6 of the unit 1 is connected to the inverting input terminal of the subtraction circuit 3, 4.5.

The signal generator 60 control input terminal is an input terminal for setting the amplitude and initial phase of the reference voltage.

The measuring device 2 is a measuring device 90 for measuring the electrical energy quality index. ..., 9, and the input terminals of these measuring instruments are combined to function as the input terminal of the measuring device 2.

Information about the Electrical Energy Quality Index can be found on meter 9. ,
...I is taken out from the output terminal of 9n.

The apparatus shown in FIG. 2 operates as follows.

The signal generator 6 is operated to form a positive phase reference voltage symmetrical system. Those voltages can be calculated using equation (6). The amplitude UM□ and the initial phase ψ1 of these reference voltages are set to the signal generator 60 control input terminal. In the subtraction circuits 3 and 4.5, the reference voltage UA1" BIT UC
l is subtracted from the phase voltages UA, UB, Uo, and the obtained differences ΔUA, ΔUBI ΔUc are used in subtraction circuits 3, 4,
5 to the measuring device 90. ...+9n input terminal. These instruments select symmetrical components. Their symmetrical components are used to determine the quality index of electrical energy.

Assume that the measuring device 9 is a measuring device that measures the positive sequence voltage. The quantity rate indication of this measuring device 91 is obtained by changing the amplitude UM1 and the initial phase ψ1 of the reference voltage. This operation can be performed automatically or by an operator.

One embodiment of the method of the invention provides that the amplitude and the first phase of the reference voltage system are the amplitude A/2U of the positive sequence voltage of the three-phase power supply network.
? is determined by measuring the initial phase.

In other words, the quantities UM0 and ψ□ are respectively the values ・, /Nu
Take awn, ψt. Normal voltage value U- and its initial phase ψ
t are those nodes ξ in the three-phase power supply network to be tested
It is obtained by measuring the parameters.

FIG. 3 shows an apparatus for carrying out this embodiment of the method of the invention. This device also includes a positive-sequence voltage compensation unit 1 and a measuring device 2 connected via this unit 1 to an input terminal.

The apparatus also includes a measuring device 10 for measuring the amplitude and initial phase of the positive sequence voltage. The input terminal of this measuring instrument 10 is connected to the input line, and its output terminal is connected to the input terminal 7 of the unit 1.
, 8. The amplitude and initial phase of the reference voltage are applied to their input terminals 7, 8.

The operating principle of this device differs only slightly from that of the device shown in FIG.

The amplitude and the initial phase of the positive sequence voltage are measured with the aid of the device 10, and the data about the amplitude and phase are input from the corresponding output terminals of the measuring instrument 10 in order to set the amplitude and phase of the reference voltage. applied to terminal 7.8. The signal generator 6 (FIG. 2) constitutes a three-phase reference voltage system. The amplitude and initial phase of this three-phase system correspond to the amplitude and initial phase of the three-phase power supply network, respectively. As a result, the differential voltage ΔU
A, ΔUB.

ΔUo does not include the positive sequence voltage, so the measurement accuracy of the quality index is not affected by errors caused by the transfer coefficient of said positive sequence voltage.

Since this variant of the method according to the invention provides the highest measurement accuracy, it can be applied to measure the electrical energy quality index in supply networks with small asymmetry and neutral shift coefficients.

Measuring only the first phase of the positive sequence voltage of a three-phase power supply network,
The value of that first phase is used to determine the first phase of the reference voltage system, and the amplitude of the reference voltage is set equal to the nominal value of the voltage of the three-phase supply network, i.e. UM□=ηUN and ψ1=ke. Hypothetical embodiments are also possible.

The operation of this device is such that the measuring instrument 10 is disconnected from the input terminal of the unit 1 and the nominal value of the amplitude of the reference voltage is set at the input terminal 7.
The operation is similar to that of the device shown in FIG. 3, except that

In this case, since the phase of the reference voltage system matches the phase of the positive-sequence voltage of the three-phase power supply network, the voltage U" - U
The positive phase of exists at the differential voltage ΔUA tΔUB, ΔUc. Since H is equal to UN, the voltage fluctuation in the three-phase power supply network can be calculated and measured from the following equation.

UN The advantages of this embodiment of the method of the invention are as follows.

First, since the amplitude of the reference voltage is set to a predetermined value,
Measurement operations become easier. Second, it is possible to measure voltage fluctuations and peak-to-peak values in a three-phase power supply network. Furthermore, the measurement accuracy of these nozzle parameters is also improved.

According to another embodiment of the invention, the amplitude of the reference voltage is determined by measuring the amplitude of the positive sequence voltage of said three-phase power supply network, the first phase of one phase voltage (e.g. human phase voltage) The first phase of the reference voltage is determined by measuring . That is, UMl =σUF, ψ□”!E, where ψ is the first phase of the voltage UA.

A block diagram of an apparatus for carrying out this embodiment of the method of the invention is shown in FIG. This device includes, in addition to the positive sequence voltage compensation unit 1 and the measuring device 2, a positive sequence voltage measuring device 11 and a former 12 connected to the line rAJ.

The input terminal of the measuring instrument 11 is the input line FA" + rBJ J
rcJ and its output terminal is connected to the input terminal 7 of unit 1. This input terminal 7 is set for the reference voltage amplitude. Former 2 is connected to line rAJ. The output terminal of the former 2 is connected to the input terminal 8 of the unit 1. This input terminal 8 is set to the value of the first phase of the reference voltage.

Therefore, the amplitude of the reference voltage is set equal to the amplitude of the positive-sequence voltage of the three-phase power supply network, and the first phase of the reference voltage is set when the voltage UA takes a zero value, so that:
etc. to the first phase] becomes 7.

When the asymmetry rate and unbalance rate decrease, the voltage U of the rAJ phase decreases.
The coefficient of the difference between the complex values of A and the complex value of the positive-sequence voltage U□ becomes small, and the coefficient of the difference between the complex values of the reference voltages TJ and IJ7 also becomes small. Therefore, as in the previous embodiment of the method of the invention, the influence of the transfer coefficient of the unmeasured parameter is reduced. Furthermore, as the value of the measured parameter becomes smaller, the subtraction circuit 3.4.5 (
The positive sequence voltage component in the output voltage (FIG. 2) also decreases.

This embodiment of the method of the invention therefore increases the measurement accuracy and widens the range of parameters that can be measured. Furthermore, in this embodiment, the first phase of one phase voltage can be easily determined by the time when the instantaneous value of the corresponding phase voltage takes a zero value, which simplifies the measurement operation.

FIG. 5 shows a block diagram of another embodiment of an apparatus for carrying out the method of the invention. In this embodiment, a symmetrical three-phase system of positive-sequence reference voltages is formed, the initial phase and amplitude of which are respectively equal to the initial phase and amplitude of the positive-sequence voltage of the three-phase power supply network.

This device includes a measuring device 9 for measuring the symmetrical component. ,...

9 and a unit 1 including subtraction circuits 3, 4.5. The input terminals of the measuring device 9 are combined, the first non-inverting input terminals of the subtracting circuits 3, 4.5 are connected to the input terminals [AJ, rBJ, rcJ, and the output terminals are connected to the measuring device 9□, . . . Connected to the input terminal of 9n. Unit 1 is a three-phase filter 3 for the symmetrical component of the positive sequence voltage.
Also included. The input terminal of this filter 3 is input terminal rAJ
, rBj, and rcJ, and the output terminals are connected to the corresponding inverting input terminals of subtraction circuits 3 and 4.5.

It is known that the output voltage of a three-phase filter with a symmetrical component of positive-sequence voltage forms a symmetrical system of positive-sequence voltage. The initial phase and amplitude of those voltages correspond respectively to the initial phase and amplitude of the positive sequence voltage of the three-phase supply network. Similar to other devices for measuring symmetrical components, the symmetrical component three-phase filter 3 has transmission coefficients for positive, negative and zero-sequence voltages. However, the asymmetry rate and unbalance rate in the three-phase power supply network are not large, and rarely exceed 5, and the value of the transfer coefficient of the three-phase filter 3 for the symmetrical component of the positive sequence voltage is 1 = D
+ 191) l K2 =azt K3 =as
(a r, << 1.

Since δ (1, δ3 (1)), the effect of voltage asymmetry and unbalance on the output voltage of the filter can be ignored. Therefore, the positive sequence voltage is actually the subtractor circuit 3, 4 .
It does not exist in the output voltage of No. 5, and the negative phase and zero phase voltages remain unchanged.

The output voltage of the subtraction circuit 3.4.5 is applied to the input terminals of measuring devices 9□, . . . , 9n that measure symmetrical components of the negative phase and zero phase voltages. Their symmetrical components are used to determine the quality index of electrical energy.

This device (FIG. 5) has a simple structure, can measure the positive sequence voltage, and can generate the positive reference three-phase voltage by one unit, ie by the three-phase filter of the symmetrical components.

The method of the invention can be implemented using the digital apparatus of the invention shown in FIG.

The device comprises adder circuits 14, 1.5, 1.6, a controlled three-phase signal generator 17, a forming circuit 18 and a symmetrical component measuring device '21). Addition circuit 14, 1.5, 1
．． The first input terminal of 6 is the input line rAj, rBJ,
Connected to rcJ. The output terminal of the signal generator 17 is connected to other input terminals of the adder circuits 14; 15, 16. The input terminal of the forming circuit 18 is connected to the input line "A" and the output terminal is connected to the synchronous signal terminal 19 of the signal generator 17. The symmetrical component measuring device has an analog memory 21,
It includes a switching device U, a voltage-to-value converter, a synchronization unit 24, and a processor section. Adder 14 t 1
The output terminals of 5+16 are connected to the input terminals of the converter 23 via the analog memory 21 and the switching device ft24, and the output terminals of each converter are connected to the information input terminals of the processor section. Data on the quality index of the electrical energy are taken off at the outputs 26, 27, 28 of the processor section, and data on the amplitude of the reference voltage are taken off at a further output 29 of the processor 2!5. This output terminal 29 is connected to a control input terminal of the signal generator 17. The control input terminals of the analog memory 21, the switching device 22 and the converter are connected to the corresponding output terminals of the synchronization unit 24.

Next, the operation of this device will be explained.

A voltage UA is applied to the input terminal of the forming circuit 18.

.xi. pulse is formed at the output terminal of this forming circuit 18 when the voltage UA takes a zero value. The pulses are applied to the input terminal 19 of the synchronization unit 9. Signal generator 1
7 forms a three-phase voltage system. The instantaneous value of the voltage of the three-phase voltage system is given by equation (6). In this case the first phase ψ corresponds to the first phase of the voltage UA (its instantaneous value d1 becomes equal to zero when said signal is applied to the input terminal 19), and the amplitude of the reference voltage UM1 is It is determined by the code P applied from the output terminal 29 of the generator δ to the control input terminal of the signal generator 17.

The synchronization unit 24 forms the signals that operate the analog memory 21. The memory 21 stores the instantaneous value of the voltage applied to the input terminal of the memory 21 when a signal is applied to the control input terminal of the memory 21. The output' voltage of the memory 21 is then applied alternately 1/rC to the input terminal of the voltage-to-value converter via the switching device R22. The control of the switching device 22 and the start-up of the converter are effected by signals provided by the corresponding outputs of the synchronization unit 24. The above-described operations of the memory 21, the switching device 22 and the converter n are performed n times during the voltage period T. The code of the instantaneous voltage value at the input terminal of the measuring device from the output terminal of the converter to the processor δ is XAi+ XBII XCI (1=O+1+...
・+n 1) is given.

X-ΔUA supervisor,) I XB1-ΔUB豐)

The phase voltage cosine component and sine component are calculated from the following equations.

The cosine and sine components of the phase voltage thus obtained are used to calculate the cosine and sine components of the positive phase, negative phase, and zero phase voltages.

1 1 1 no kaa,=a a h-a a B-s k c + a
b n ”' fC5= i, , 1-5-1.-
J5a+ff+.

1 3A6B6C6B 6C a = '-a -'-a -'a-nbJb2 3
A6B6C6B 6C 5=15-1. -15+sl”i, -4323A6B
6C6B 6C Yu = = La +2-a Ja 3 3A6B6C b = Lb Jb 1''-b 3 3A6B6C And those components are used to calculate the current values of the positive and negative phase voltages. In this case, , circuit 1.4
, 15, and 16 include the positive phase reference voltage system, it is necessary to add the cosine and sine components of the reference voltage system to the cosine component a and the sine component b1. . The cosine component and sine component of the reference voltage system are each 0 + UM 1 (the reason why the cosine component is zero is because the zero time reference coincides with the time when the voltage UA takes the zero value). . In the case of , it is U1''-E sales review + U2 ``a U''f5 diagram.

The electrical energy quality factor is determined from the values U-, U-, U: That is, the voltage fluctuation V is taken out from the output terminal of the processor δ, the asymmetry factor δ2 is taken out from the output terminal 27, and the unbalance rate ε2-1·100chN. is pulled out from the output terminal path.

Also, information is taken out from the output terminal 4 of the processor δ in the form of a code equal to 2U-. The code P is used to set a new value of the reference voltage amplitude.

Apart from the above-mentioned quality index of at-temperature energy, the device according to the invention can also be used with other indexes, such as the distortion factor of the sine wave, the harmonic level in the phase voltages, and other A-meters that can be determined from the core of the voltage instantaneous value. It can also be used to determine For example, the distortion factor of the sinusoidal voltage UA is determined from the following equation.

iUN The performance of this operation does not require any changes to the structure of the device of the invention. This operation is carried out using a corresponding processing program loaded into the processor section.

The main advantages of this embodiment of the device of the invention are: (1) it has a wide range of applications since it can measure all quality factors of electrical energy; (2) the amplitude of the reference voltage is controlled during the determination of the quality factor of electrical energy; (3) By using the measuring device silver as a zero indicator of the positive sequence voltage, i.e.,
The accuracy of the device can be increased by changing the amplitude of the reference voltage so that the cosine component a1 and the sine component b1 approach zero.

In the embodiment of the apparatus according to the invention shown in FIG. 6, the control signal generator 17 (FIG.
D-A) Contains converter blades 31 , 32 , 33 , a constant generator 34 , a counter 35 , a frequency multiplier 36 , and a register 37 .

The output terminals of the D-A converters 30 and 31132 function as output terminals of the signal generator 17 and adder circuit 14.

15 and 16, respectively.

1) The control input terminals of the -A converters 30 e 3i , 32 are connected via a constant generator 34 to the output terminal of the counter. A count input terminal of this counter 35 is connected to an output terminal of a frequency multiplier 36. The input terminal of this frequency multiplier 36 is combined with the reset input terminal of the counter 35 and functions as the synchronization input terminal 19 of the signal generator 17. The analog input terminals of the DA converters 30, 31, and 32 are connected in combination to the output terminals of each DA converter. The DA converter 330 control input terminal is connected to the output terminal of register 37. The input terminal of this register 37 is the signal generator 170 control input terminal.

Next, the operation of the signal generator 17 will be explained.

The code UM□ taken out from the processor is low-Peded to the register 37. Since the D-A converter is connected to the output terminal of the resistor 37, a constant voltage -UM□ is applied to the output terminal of the D-A converter (the reference voltage is in reverse phase with the input voltage). Since it is necessary that this voltage −
UM□ is negative).

has a duration equal to the period T of the voltage UA and input terminal 1
The signal applied to the counter 9 is applied to the reset input terminal of the counter 35 and the input terminal on the frequency multiplier side. This frequency multiplier 36 forms a noggle with a duration equal to T/n. Counter I has n stable states.

In response to each row )'i (t=0. Those codes are D-A converter blades.

It is applied to control input terminals 31 and 32.

From the output terminal of the DA converter 33 to the DA converter (2).

Since voltage -UMl is applied to the analog input terminals of 3], , and 32, the output voltage of these DA converters becomes .times.3]. The output voltage waveform of the signal generator 17 is a stepped sinusoidal waveform, but since the instantaneous value of the voltage at the input terminal of the measuring instrument is converted to low P only at time Ti/n, it affects measurement accuracy. Therefore, during said time the variation law of the reference voltage is not manifested by itself.

Since the control three-phase signal generator is configured in this way, it does not include an inertial element, so the response speed is high and the accuracy can be maximized. Its accuracy is determined by the accuracy of the DA converter. Also, this structure allows direct control of the output code of the meter.

In another embodiment of the controlled three-phase signal generator, the first phase of the reference voltage is set. This phase setting operation is such that the signal generator includes another register whose input terminals are connected to the control input terminals of the signal generator 17, whose input terminals are connected to the processor 5. This can be done to connect to the output terminal of the The output terminal of the register is connected to the reset input terminal of the counter 35.

The principle of operation of the signal generator 17 is that a signal at the input terminal 19 causes the counter 35 to enter state q. unchanged except for resetting to . That signal is loaded into register 38.

In this case, the initial phase of the reference voltage is -2π 　　　nO and t"ru.

The block diagram of the signal generator 17 allows a complete compensation of the positive sequence voltage at the input terminal of the measuring instrument (A), thereby improving the measurement accuracy of the electrical energy quality.

[Brief explanation of the drawing]

Fig. 1 is a lightning five-voltage vector diagram, Fig. 2 is a block diagram of an apparatus for carrying out the method of the present invention, Fig. 1 is a Zorock diagram of an apparatus for carrying out the method of the present invention, and Fig. 4 is a block diagram of the apparatus for carrying out the method of the present invention. FIG. 5 is a block diagram of an apparatus for carrying out another embodiment of the method of the invention; FIG. 6 is a block diagram of an embodiment of the apparatus for carrying out the method of the invention; FIG. FIG. 7 is a block diagram of a three-phase signal generator included in the apparatus shown in FIG. 3.4.5... Subtraction circuit, 9... Measuring device for measuring the symmetrical component of the positive sequence voltage, 13... Symmetrical component three-phase filter, 14, 15, 16... Addition circuit, 17. ... Three-phase signal generator, 18... Forming circuit, Adding... Three-phase voltage symmetrical component measuring device, 30°31, 32, 33... Digital-to-analog converter, 34... Constant forming device ,a·
...Counter, 36...Frequency multiplier, 37゜38
···register. Applicant's agent Kiyoshi Inomata Continued on page 1 0 Inventor Sergei Darebovich Taranov Soviet Union Kiev Brestolitovsky Prospekt 2 Karbe 108 0 Inventor Isaak Pavlovich Grinberg Soviet Union Sitmir Uritsutsa・Kororenz 5/20 Rikiichibe-42 0 Inventor Bordomir Vasilyevich Bryko Soviet Union Kyiv Uritsutsa Semashko 12 Karbe 42 0 Inventor Roman Mikhailovich Galitsky Soviet Union Sitmir Uritsutsa Engelsa 3 Karbelo 8 0 Inventors Oleg Leonovich Karasinsky Soviet Union Author: Reitaly Vladimirowitch Sobotovich Soviet Union Sitomir 2 Pereulok Chekhova 65 0 Inventor: Rafeil Benedict Witch
Kushid Soviet Union Sitomir Ulitsya Chabaeva 17 Kabe 44 [Phase] Inventor Alexander Mifuodeyevich Tsyganok Soviet Union Sitomir Uritsutsa Korolenko 10 A Kabe 59 0 Inventor Viktor Alekseevitch Ya Shuk Soviet Union Sitomir Uritsutsa Lenina 98 be Rikiichibe - 269 0 Inventor Vera Rafaylona Gilgurd Soviet Union Sitomir Uritsutsa Golkovo 42 Kabe 9 0 Inventor Babel Stepanovich Smanev Soviet Union Sitomir・Wuritza Chehova 20a・Rikiichibe-23

Claims (1)

[Claims] 1. Quality of electrical energy in a three-phase power supply network, comprising a process for determining a symmetrical component of the three-phase power supply network having a magnitude used to determine the value of a quality index of electrical energy. A method for determining the index, first determining the amplitude and the first phase of the reference voltage, then forming a positive symmetric three-phase voltage reference system, the first phase and amplitude of the reference system being equal to the first phase of the reference voltage. First equal to the previously determined values of phase and amplitude, the frequency of the same reference system is equal to the frequency of said three-phase power supply network, then the reference voltage is subtracted phase by phase from the input voltage, and the input voltage and the reference The thus obtained difference in voltage is a method of determining the quality index of electrical energy in the power supply network. 2. The method according to claim 1, wherein the amplitude and initial phase of the reference voltage are determined by measuring the amplitude and initial phase of the positive sequence voltage in the three-phase power supply network. A method characterized by: 3. The method according to claim 1, wherein the amplitude of the reference voltage is taken equal to the nominal value of the amplitude and the first phase of the positive sequence voltage in the three-phase power supply network is determined. A method characterized in that it determines an initial phase. 4. A method according to claim 1, in which the amplitude of the reference voltage is determined from the amplitude of the positive sequence voltage in the three-phase power supply network, and the first phase is determined from the amplitude of the positive sequence voltage in the three-phase power supply network, e.g. A method characterized in that the rAJ phase voltage is determined from the first phase of the rAJ phase voltage. 5. A device for determining the quality designation of electrical energy, wherein the measuring output terminal for measuring the three-phase voltage symmetrical component is the output terminal of the device, and the output signal of the measuring device (20) is the In a device for determining the quality index of electrical energy, which represents information about the value of the quality index, three adder circuits (14), (15), (
16), a control three-phase signal generator (17), and a forming circuit (
18), and the addition circuit (14), (L5)
, (ta) serves as an input terminal of the device, and the output terminal of the summing circuit is electrically connected to the corresponding input terminal of the measuring instrument (20) for measuring three-phase voltage symmetrical components. connected to the control three-phase signal generator (1
The output terminals of 7) are adder circuits (14), (15),
(16), the control input terminal of said controlled three-phase signal generator is connected to the output terminal of said measuring device (20) for measuring three-phase voltage symmetrical components; ) is connected to a synchronous input terminal of a three-phase signal generator (17), and the input terminal of said forming circuit is connected to one input terminal of said device. A device that determines. 6. The device according to claim 5, wherein the controlled three-phase signal generator (17) includes three digital-to-analog converters (30), (31), (32) and a fourth
digital-to-analog converter (33) and register (3
7), a constant generator (34), a counter (35),
a frequency multiplier (36), and the output terminals of the digital-to-analog converters (30), (31) and (32) are output terminals of a controlled three-phase signal generator (17);
The output terminal of the fourth digital-analog converter (33) is connected to the three digital-analog converters (30),
(31). (32), the input terminal of the register (37) is the control input terminal of the control three-phase signal generator (17), and the output terminal of the register (37) is the fourth digital signal generator (37). - connected to the input terminal of the analog converter (33), the output terminal of said constant former (34) being connected to the first
．． Second. Third converter (3o), (31). (32) is connected to the input terminal of the counter (35).
The output terminal of the frequency multiplier (36) is connected to the input terminal of the constant generator (34), and the output terminal of the frequency multiplier (36) is connected to the input terminal of the constant generator (34).
35), the input terminal of the frequency multiplier is combined with the synchronous reset input terminal of (35), and is the synchronous input terminal of the control three-phase signal generator (17). device to do. 7. The device according to claim 6, wherein the control three-phase signal generator (17) further includes a second register (38), and the input terminal of the second register is connected to the control three-phase signal generator (17). connected to the control input terminal of the phase signal generator (17);
A device characterized in that the output terminal of the register is connected to the reset input terminal of the counter (35). 8. A device for determining the quality index of electrical energy, which measures three-phase voltage symmetrical components (9,...9)
, the number of these measuring instruments is equal to the number of quality indices to be measured, the output terminal of said measuring instrument measuring the voltage symmetrical component is the output terminal of said device, and the output signal of said measuring instrument is equal to the number of quality indices to be measured In the device for determining the quality index of electrical energy, which represents information about the quality index of (13), each output terminal of the subtraction circuit is connected to a corresponding input terminal of each measuring device (9, . . . 9) that measures three-phase voltage symmetrical components, and an input terminal of a three-phase filter. is the subtraction circuit (3)
, (4) and (5), and the output terminals of the three-phase filters are connected to corresponding subtraction circuits (3) and (4). (5) A device for determining the quality index of electrical energy, characterized in that it is connected to the inverting input terminal of (5).