A device for comparing two signals, the device and method of formation of non-stationary signals

 

(57) Abstract:

The invention relates to a device for comparing two complex vector quantities in real time and can be used for the formation of non-stationary signals. The technical result is to accelerate the comparison of two signals. The invention uses digital methods based on the properties of the cylindrical device for comparing complex vector quantities in real time, in one case, a signal of the rotational moment generated by the digital comparator, to detect the presence of a failure in the transmission line, in the other case uses the output signal to determine the direction of power flow in the transmission line, in the third case, to determine, exceed or there is no voltage or current specified threshold level. 3 C. and 20 C. p. F.-ly, 10 ill.

The scope of the invention

This application is isolated from the application N 97108360, which, in turn, filed on the basis of the international application PCT/US95/12739.

The present invention relates to a device for comparing two complex vector quantities in real time and the formation of non-stationary signals.

Relay Eiseman power or power: (a) the monitoring system for identifying if the system is in normal condition or not; (b) measurements, which include the measurement of some electrical quantities; (c) protection, which usually includes a trip switch circuit upon detection of a short circuit; and (d) alarm that provides a warning of some difficult circumstances. When these and other additional functions, such as failure detection, the determination of the direction of power flow, the detection of the maximum current and other systems of relay protection must compare two complex vector quantities (voltages and currents). Usually, the sooner such a comparison can be made, the better.

2 To the present invention, a protective relay, as a rule, compared complex vector values using frequency domain methods, such as the method of Fourier transform.

As the nearest analogues in relation to the claimed invention in a device for comparing two signals, you can specify the device according to U.S. patent N 5151866 published 29.09.92 G 06 F 15/20, NAT. CL 364/483 containing, in the same way as the claimed device, the means for calculating the phase difference. However, this device neoba and formation of non-stationary signals of positive and negative symmetrical sequence component currents of a power system can be specified on the method of formation of non-stationary signals symmetric sequence component, includes the operation of receiving the digital values of the symmetric component in real time, as described in the digital recording system for U.S. patent N 3740491 published 19.06.73, NAT. CL 360/27, and a digital comparator that is designed for the formation of non-stationary signals, including means for sampling to obtain samples, means for multiplying and summing means described in U.S. patent N 3500322 published 10.03.70, NAT. CL 340/146.2.

These two technical solutions do not enable the formation of non-stationary signals, which can be used in the inventive device for comparison in real time between the two signals.

The main aim of the present invention is to develop methods and devices for comparison of complex vector quantities in real time.

BRIEF DESCRIPTION OF THE INVENTION

The invention uses digital methods based on the comparison of complex vector quantities in real time. Unsteady procedures in this description, compare complex vector magnitude faster than any previously known method.

Applying the device for comparison in real time between the two signals, and tastey component voltages and currents in the power system.

Device for comparison in real time between the two signals (S1(t) S2(t)), each of which is represented by magnitude and phase, provides a means of sampling to obtain a set of samples of each of the two signals representing the magnitude of each of the two signals at least at two different points in time, and computing means for calculating moment Mk+1corresponding to the phase difference of two signals on the basis of samples. Means for sampling selects the reference (S1krepresenting the magnitude of the first of these signals in the first time, selects the reference (S2krepresenting the value of the second of these signals in the same first point in time; allocates count (S1k+1representing the magnitude of the first of these signals in the second time, and selects the reference (S2k+1representing the value of the second of these signals in the same the second time, and the computational means includes means for obtaining the derivative values B1k, B2k, B1k+1and B2k+1for samples S1k, S2k, S2k+1tool multiplication for multiplying the values B1kB2k+1and multiplying the quantities B2kon B1k+1to obtain prilojeniya the first and second compositions to obtain the result of the calculation (Mk+1) corresponding to the phase difference between the first and the second complex vector value, and the values B1kand B2kare using the following ratios:

B1k= FK2[S1k+ S1k-1FK1B1k-1] ,

B2k= FK2[S2k+ S2k-1FK1B2k-1] ,

where FK1 and FK2 are constants and are determined by the following relations:

,

,

where RB and LB are constants.

The samples S1kand S2kobtained by sampling the voltage or current in the transmission line, and the signals S1(t) and S2(t) represent the voltage or current varying in a sinusoidal manner, or a combination of voltages and currents.

Provided that the device also includes means for using the obtained result of the computation Mk+1to determine whether there is damage in the specified transmission line to detect interfacial failure in the system of three-phase transmission line, where the samples S1(t) and S2(t) are obtained from interfacial stresses and complex currents, for failure detection phase and earth in the system of three-phase transmission line; a S1(t) and S2(t) are obtained from the voltage between phase and earth and complex currents and to determine the direction of power flow in the PE component are the input signals of the device for comparison.

Preferably, the device for comparison additionally contain means for subtracting a predetermined constant (MS) from the results of the computation of Mk+1and use the difference Mk+1- MS for receiving the signal (qk+1), which defines the energy contained in the differential signal S1(t) S2(t);

means for using the obtained result of the computation Mk+1in order to determine, exceeds or not the voltage or current in the transmission line specified threshold level;

and the scaler to convert the received result of the calculation (Mk+1), which multiplies the result by a specified factor proportional to the sampling period.

The method of formation of non-stationary signals symmetric positive sequence component (I1) and negative symmetrical component sequences (I2) current supply system, includes obtaining samples of these currents to the power system and the use of digital logic circuits to obtain digital values of the symmetric component (I1, I2) in real time, which include systems of delay elements, reinforcing members and summaryimage, moreover, the digital logic circuit form a symmetrical components, proportional Ilk and I2k, and I1 represents a current of positive sequence, I2 represents a current negative sequence, the subscript k refers to the digital samples of the respective component.

Digital logic schematic form the components Clarke

I = 3I1+3I2 = 2Ia-Ib-Ic,

,

moreover, this power supply system includes a first phase (phase-a), the second phase (phase-b) and third phase (phase-c), where Ia is the current in phase-a, 1b represents the current in the phase-b and Ic is the current in phase C.

Digital logic circuits receive the samples Ia, Ib and Ic; form values IakIak-1, Ibkand Ibk-1; and then there are combinations of values IakIak-1, Ibkand Ibk-1to obtain values I1k, I1k-1, I1k-2, I2kI2k-1and I2k-2.

Provided that the power supply system includes a first phase (phase-a), the second phase (phase-b) and third phase (phase-c), and digital logic circuits receive the samples Ia, Ib and Ic; form values IakIak-1, IbkIck-1and Ick-1and then make up combinations of values Ia

Apparatus for forming non-stationary signals symmetric positive sequence component and the negative symmetric sequence component of the voltages and currents of the power supply system includes means for sampling to obtain samples of these currents of the power system and the digital logic circuit for forming a symmetric positive sequence component (I1) and negative symmetrical component sequences (I2) current supply system, including a system of delay elements, audio elements and summary elements, United in working condition for the formation of symmetric digital real-time component, wherein the digital logic circuit form a symmetrical components, proportional I1k and I2k, and I1 is a current of positive sequence, and I2 represents a current negative sequence, the subscript k refers to the digital samples of the respective component.

Provided that the power supply system includes a first phase (phase-a), the second Pazos,

,

where Ia is the current in phase-a, Ib is the current in the phase-b and Ic is the current in phase c.

Digital logic circuits include a first input terminal for receiving samples of the current Ia in phase a and the second input terminal for receiving samples of the current Ib in phase-b, and a third input terminal for receiving samples of the current Ic in the phase-c; means for forming a value IakIak-1, Ibkand Ibk-1; and means for combining values IakIak-1, Ibkand Ibk-1and get the values I1k, I1k-1, I1k-2, I2k, I2k-1and I2k-2.

Provided also that the power supply system includes a first phase (phase-a), the second phase (phase-b) and third phase (phase-c), and digital logic circuits include a first input terminal for receiving samples of the current Ia in phase a and the second input terminal for receiving samples of the current Ib in phase-b, and a third input terminal for receiving samples of the current Ic in the phase-c; means for forming a value IakIak-1, Ibk, Ibk-1Ickand Ick-1and means for combining values IakIak-1, Ibk, Ibk-1Ickand Ick-1to obtain a value is a current in phase C.

It should be noted that this invention provides a relay protection means comparing the phase relations S1 and S2, as well as the energy content of the two total signals. No other known numerical method used in industrial research, has no ability to change their work depending on the energy content of the input signals S1 and S2. This characteristic is necessary in applications of relay protection, in which the working range is inversely proportional to the energy content. Other methods such as the method of Fourier filtering is widely used in industrial studies do not provide such an inverse relationship. The processing speed does not depend on the energy content of the input signals.

Thus, the input signals S1 and S2 digital comparator define the characteristics of the created device. Numerous applications of digital comparator below include relay protection, discussed above, and others.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 schematically shows the input supply system for the application of relay protection and/or application of the digital comparator.

Fig. 3A is a block diagram of a digital comparator in accordance with this invention. In this embodiment of the present invention calculates the Mk+1in real time, and Mk+1corresponds to the angular moment of the cylindrical device.

Fig. 3B shows a complex vector of characteristics of the digital comparator shown in Fig. 3A. Fig. 3B shows a complex vector of characteristics of the cylindrical device, shown in Fig. 2A, which are similar to the complex vector characteristics of the digital comparator and the output signal M

Fig. 4A shows a circuit that simulates the equations defining the input signals to the interface device determining the distance based on the digital comparator in accordance with this invention.

Fig. 4B is a block diagram of one embodiment of interface device determining the distance from the operator of the delay "d".

Fig. 4C shows a circuit that simulates the equations defining the input signals of the device determine the range of the values of the phase-to-ground on the basis of the digital comparator in accordance with this invention.

Fig. 4D pred accordance with this invention.

Fig. 5A shows the desired characteristic of the directional device in the R-X plane. Aiming devices listed in this description, have this characteristic.

Fig. 5B illustrates an idealized cylindrical device and the relation between M (torque) and (angle).

Fig. 5C - 5F show the processing performed directional devices with digital comparator in accordance with this invention.

Fig. 6A shows the symmetric components of the analog filter.

Fig. 6B and 6C schematically show options filter with symmetrical components in accordance with this invention.

Fig. 6B shows a filter with symmetrical components Clarke.

Fig. 6C shows a filter with symmetrical components and direct phase shift.

Fig. 7 schematically shows one variant of the device maximum current (at the entrance of which can serve as signals of voltage and current signals) and its implementation with the separation of the comparator in accordance with this invention. (Note that many devices on the basis of the digital comparator using the separation comparator that avaliale the comparator.

Fig. 8B schematically shows one version of the digital separation of the comparator in accordance with this invention.

Fig. 9 schematically shows the functional characteristic of the separation of the comparator.

Fig. 10 is an illustrative graph of the output signal of the dividing of the comparator.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

A. OVERVIEW

Relay protection is a method of protecting electrical equipment, receiving the voltage or current from the system power supply. System relay protection requires certain input signals from the transmission line 10, which consists of three phase conductors A, B, C. Fig. 1 shows the standard way to obtain the required input signals. It is seen that the input voltage signals VA, VB, VC are obtained using a transformer voltages 12, and the input current signals IA, IB, IC are obtained using a current transformer 14. Values for the relay 16 are integrated voltages VA, VB, VC; the zero-sequence voltage - 3V0 = VA+VB+VC; complex currents IA, IB, IC; and the current zero-sequence - 3I0 = IA + IB + IC.

B. em a device, used in a protective relay, to compare two complex vector of values for the phase and/or magnitude. A cylindrical device 18, schematically shown in Fig. 2A, is a well-known type comparator used in Electromechanical relays. Two distinctive characteristics of this cylindrical device is its insensitivity to the offset DC current and high speed.

When two signal voltages S1 and S2 are served on a cylindrical device 18, having density of streams B1 and B2. These density flows are characterized by a vector distribution on the surface of the rotating cylinder. If B1 and B2 nonstationary, the cylinder excitatory currents, and these currents is proportional to the rate of change of B1 and B2 represented by the values dB1/dt and dB2/dt, and angle theta (), which represents the phase difference between the signals S1 and S2. These currents cylinder is directed along the positive direction of Z-axis (i.e. perpendicular to the plane of Fig. 1). Using equation vector forces (see below), can be found field vector forces on the surface of the cylinder

.

The interesting quantity is the torque about the axis Z. This moment the next way is expressed through the density of streams B1 and B2:

< / BR>
or

,

where is the electrical conductivity (Cm/m);

= 3,1415;

r = radius of the cylinder;

l = length of the cylinder;

T = thickness of the cylinder.

If two time-dependent voltage signal S1(f) and S2(t) are served on a cylindrical device 18, is excited by a time varying flux density B(f). This flux density B(t) has components B1(f) and B2(f) associated with S1(f) and S2(t) by the following relations:

,

,

,

,

where N1 and N2 the number of turns of the input winding of the signals S1 and S2.

It should be noted that these equations do not contain any mechanism loss. These ratios include loss and can be used to determine S (input signals) through value B.

,

,

where LB and RB constants, determined to make the model more effective.

If the signals S1(f) S2(f) is a sine wave so that

S1(t) = Sin(t),

S2(t) = Sin(t+)

the torque (expressed in fractions of a unit) will equal

M = 0 when = 0;

M = -1 when = 90;

M = 0, when = 180;

M = 1 when = 270< / BR>
as shown in Fig. 2B.

When is there to be converted into discrete form using the trapezoidal rule

< / BR>
and

,

B1k= FK2[S1k+ S1k-1- FK1B1k-1] ,

B2k= FK2[S2k+ S2k-1- FK1B2k-1] ,

in which

,

< / BR>
and torque can be expressed in the following form:

Mk= B2kB1k-1- B1kB2k-1,

where k+1 = current reference

k = previous reference

t = the sampling period.

Fig. 3A is a block diagram schematic of a digital comparator or system 20 to calculate the Mk. In the system of Fig. 3A "d" denotes a delay device; means summing device; "P" denotes a multiplier, and FK1 and FK2" refers to the amplifiers. The output signal Mksystem 20 represents a torque of Mkreal-time comparator, having a complex vector characteristics shown in Fig. 3B, illustrating the operating characteristics of the digital comparator 20. Taking the signal S1 for the reference level, the phase difference fromoto -180omatch the working range of the device. The phase difference from 0oto +180omeets or outside the bounding range of the device.

This procedure can be used in relay-range control. in which it is desirable comparison of real-time two complex vector quantities. In special applications of the present invention, the mechanical influence, such as a force limiting spring, friction force and/or power offset can be taken into account in the model.

C. a DEVICE for DETERMINING the DISTANCE TO DETECT FAILURES

The procedure of implementation of the device determining the distance using a digital comparator is shown below.

Relay protection is associated with the detection of failures in the power supply devices. In relay protection transmission line is used relay range to detect several types of failures of the transmission line. These devices detect faults in transmission lines to a certain extent or range. In General, these devices measure the impedance, which is proportional to the distance from the relay location to the fault-location (hence the title "device for determining the distance"). Digital devices determine the range in accordance with this procedure detect failures faster known detectors failures, and in all other respects, has characteristics similar to Electromechanical devices for determining the distance. Digits the region. This is due to the similarity with a cylindrical device that has good performance in the presence of transients.

1. THE INTERFACE DEVICE

Upon detection of interfacial failure digital input signals of the comparator are

S1 = VA - VB - (IA - IB)

S2 = VC - VB - (IC - IB).

The circuit shown in Fig. 4A, simulates these equations. Therefore, S1(f) S2(f) can be obtained from phase-to-phase voltages and currents as follows:

,

.

If you convert these equations in discrete form and apply them to model a cylindrical device discussed above, you will get

,

,

which are the input signals of the digital comparator (also called the "generator torque"), derived earlier. S1kand S2kare then used to obtain B1kand B2kas specified above.

The above equations are the discrete implementation phase transfer device determining the distance that detects all types of failures in two phases, as well as some faults phase-to-phase-to-ground.

Fig. 4B is a block diagram of one implementation of the above equations in the case of the interphase USDA detained counts the Delta voltages Vab and Vcb. Each combination is an input signal of the digital comparator 20A, which is similar to the digital comparator 20, above. The output signal of the digital comparator is fed to a restrictive device, denoted by "MM" and included in the separation of the comparator 30 (see description below). The equations for B1 and B2 are solved and the cross-product B1kB2k+1and B1k+1B2kused to retrieve the member Mk. Amplifiers denoted by "A00", "B00", "CC", "EE", "FF", "FK1", "FK2" in accordance with their gains in the following list:

A00 = Rc+Lc/t

B00 = Lc/t

CC = t2/I

EE = I/(I+t2KC/I+tKD/I),

FF = 2+tKD/I

FK1 = (2LB-tRB)/t,

FK2 = t/(RB+2LB).

(Note that CC and FF refer to divider comparator).

2. A DEVICE THAT USES THE MAGNITUDE OF THE PHASE-TO-GROUND

The input signals are well known devices for detecting faults between phase and earth have

S1 = VA - IA - K0I0)Zc,

S2 = VC - VB,

where

,

Zc = Rc+jXc = Rc+j2fLc,

.

In Fig. 4C presents a simplified diagram that models the above equation. If these equations are to be converted into discrete form and apply to the equations of the digital comparator, operator, depicted above.

Fig. 4D is a block diagram of a variant of a device that uses the magnitude of the phase-to-ground, in accordance with this invention. Shows current and voltage is discretized and combined in adders, as shown, and then fed to the inputs of a digital comparator 20b. Members B1 and B2 then cross-multiplied, the result is the value of Mkand she served on the separation of the comparator 30 (see description below). Amplifiers denoted by. "A01", "B01", "C01", "E01", "CC", "EE", "FF" in accordance with their gains in the following list:

A01 = Rc+Lc/t

B01 = Lc/t

C01 = (KrRc-KIXc)/3+(KrXc+KIRC)/3t,

E01 = (KrXc+KIRC)/3t,

CC = I/(I+t2KC/I+tKD/I),

EE = t2/I

FF = 2+tKD/I.

Thus, the above General procedure of implementation of the device impedance measurement device to determine the distance). These devices have high performance because they require only three of the sampling period (k-1, k, k+1) to obtain a criterion of separation regardless of the sampling frequency. Moreover, other devices for determining the distance can be implemented in accordance with the procedure outlined here. The above device to determine transmission is also grounded determination device range quadrature offset), are just two examples of the different principles used in relay protection to create a device definition range. The above procedure allows you to obtain any type of device definition range, currently used in industrial studies, to compare two complex vector quantities.

D. DIRECTIONAL DEVICE

Aiming devices are devices that are used in relay protection to determine the direction of power flow. Grounded aiming device on the basis of the digital comparator shown above are fast, making them ideal devices for application in relay protection and collaboration with the devices of determining the distance based on the digital comparator.

Fig. 5A illustrates the directional characteristics of such devices in the R-X plane. In this example, the forward direction corresponds to the power flow in the transmitting line. The reverse direction corresponds to the power flow of the transmission line.

Aiming devices are divided into two categories: phase directional device and grounded aimed device. Phase nepravda power system is not balanced. Developed the following directional device:

1. DIRECTIONAL DEVICE WITH OFFSET NEGATIVE SEQUENCE

Using the output signals of the digital filter with symmetrical components, the following equations can be used to implement directional device with offset negative sequence:

B1k= FK2(V2k+ 2V2k-1+ V2k-2- FK1B1k-1)

B2k= FK2(I2k+ 2I2k-1+ I2k-2- FK1B2k-1)

Mk= B2kB1k-1- B1kB2k-1.

In the above equations V2 and I2 are output signals of the digital filter with symmetrical components. This example is discussed below.

2. DIRECTIONAL DEVICE WITH OFFSET ZERO SEQUENCE

The following equations can be used to implement directional device with offset zero sequence:

B1k= FR2(3V0k+ 23V0k-1+ 3V0k-2- FK1B1k-1)

B2k= FK2(AA3I0k+ AB3I0k-1+ BB3I0k-2- FK1B2k-1)

Mk= B2kB1k-1- B1kB2k-1,

where

,

,

AB = AA + BB.

In the above equations 3V0 = VA+VB+VC and 3I0 = IA+IB+IC.


,

B2k= FK2(Ipolk+ 2Ipolk-1+ Ipolk-2- FK1B2k-1)

Mk= B1k-1B2k- B2k-1B1k.

4. PHASE DIRECTIONAL DEVICE

Phase directional device can be created by implementing the following equations:

B1k= FK2(-VCBk- 2VCBk-1- VCBk-2- FK1B1k-1)

B2k= FK2(AAIAk+ ABIAk-1+ BBIAk-2- FK1B2k-1)

Mk= B1k-1B2k- B2k-1B1k,

where

,

,

AB = AA + BB

and VCB is the Delta voltage (VC - VB).

Other directional devices can be implemented on the basis of the digital comparator above. The above equations define the "torque" of the device, which can be combined with digital dividing comparator.

Fig. 5C - 5F show the processing performed in the targeted devices.

Fig. 5C illustrates the flow of data in grounded directional device with offset negative sequence, which includes a digital comparator 20C and dividing the comparator 30. Veni grounded directional device with offset negative sequence involves combining samples V2 and I2 for the education of the members B1 and B2 and then cross-multiply to obtain the member Mkserved on dividing the comparator 30. Amplifiers, denoted by "CC", "EE", "FF", "FK1 and FK2", you have the following gains:

CC = I/(I+t2KC/I+tKD/I),

EE = t2/I

FF = 2+tKD/I

FK1 = (2LB-tRB)/t,

FK2 = t/(tRB+2LB).

Fig. 5D illustrates the flow of data in grounded directional device with offset zero sequence. Members 3V0 and 3I0 obtained from real samples values of the system power supply (3V0 = VA+VB+VC and 3I0= IA+IB+IC). Solving equations grounded directional device with offset zero sequence involves combining samples 3V0 and 3I0 for education of the members B1 and B2, which are the input signals of the digital comparator 20d, and cross-multiplying the receiving member Mkserved on dividing the comparator 30. Amplifiers, denoted by "AA55", "BB55" and "AB55 have the following gains:

,

,

AB55 = AA55 + BB55.

Fig. 5E illustrates the flow of data in grounded directional device with a current offset, which includes a digital comparator 20E and dividing the comparator 30. Input 3I0 digital comparator is obtained from real samples values of the system power supply (3I0 = IA+IB+IC) is istemi power. Solving equations grounded directional device with a current bias involves combining samples 3I0 and Ipolfor education of the members B1 and B2 and cross-multiply to obtain the member Mkserved on dividing the comparator.

Fig. 5F illustrates the data flow in the phase directional unit (phase A), which includes a digital comparator 20f and dividing the comparator 30. The input signal VCB digital comparator is equal to VC - VB, where VC and VB represent the real samples the voltage of phase C and B. IA is the integrated current of phase A. the Solution of equations of the phase directional device includes combining samples VCB and IA for the education of the members B1 and B2 and cross-multiply to obtain the member Mkserved on dividing the comparator. Amplifiers, denoted by "AA52", "BB52" and AB52 have the following gains:

,

,

AB52 = AA52 + BB 52.

The above procedure is a standard procedure for directional devices. Specialists in this field understand that other directional devices can be implemented on the basis of the proposed invention.

That is, the FILTER is SYMMETRIC COMPONENT

1. MODELING OF THE EXISTING ANALOG FILTER

Fig. 6A shows an analog filter. Components of positive and negative sequences in discrete form is given by the following equations:

,

where

< / BR>
and

,

where

.

Constants C1, R1, C2 and R2 can be carefully chosen to obtain the following optimized equations. There is a set of constants R1, C1, R2 and C2, which provides the minimum error and the correct phase shift.

2. DIRECT PHASE SHIFT

Equations symmetric component have the form

,

.

These equations can be implemented using the phase-shifting identities

,

.

Therefore, in discrete form get

,

.

3. THE OUTPUT COMPONENT CLARK

By definition, components Clarke equal

I = 3I1+3I2 = 2Ia-Ib-Ic,

.

It follows that

,

.

Using the operator

< / BR>
PoA implementation is simple. However, the subsequent operation timing in relation to derivative should be made to reduce error and improve the accuracy of the method

,

.

Fig. 6B and 6C schematically show an illustrative filter variants of the symmetric component in accordance with procedure 3 (components Clarke) and 2 (direct phase shift), respectively.

Fig. 6B shows the Union of samples IA, IB and IC to obtain the component I, I and the subsequent manipulation in accordance with the above equations to obtain I1 (positive) and I2 (negative) component of the currents. The same process can be performed for voltages for the positive and negative sequence component voltages. Amplifiers, denoted by "A" and "B" have the following odds

A = 1/4,

B = 1/(4ft).

Fig. 6C shows the Union of samples IA, IB and IC using the direct equivalent phase shift (A and B are constants) to obtain the component currents I1 and I2. A similar procedure can be used for the positive and negative sequence component voltages. In this embodiment, the amplifier "A" and "B" are coefficients gain is below, uses a digital algorithm that is fast and does not deteriorate when the DC offsets. It can be used as a level detector for voltage or current.

To implement odnorodnogo device maximum current one of the input signals of the digital comparator must be shifted in phase. Using this criterion, the following equations can be used to implement the device, the maximum current is not affected by the effects of DC offset. This device is ultra-fast.

B1k= FK2(IAk+ IAk-1- FK1B1k-1)

B2k= FK2(IAk+ 2IAk-1+ IAk-2- FK1B2k-1)

Mk= B1k-1B2k- B2k-1B1k.

This output signal "torque" (Mk) may be submitted in digital dividing the comparator and opposite constant torque can be used to adjust the level of separation. In the above equations IA can be current, voltage or any other amount of power (such as for example, the symmetric component).

Fig. 7 schematically shows a variant of the device is of narator in this embodiment are obtained, as shown, only the magnitude of IA. The samples are combined to obtain the values of B1 and B2 in accordance with the above equations. The output signal Mkcan be digital dividing the comparator 30, described below. Amplifiers "FK1 and FK2" have the following gains:

FK1 = (2LB-tRB)/t,

FK2 = t/(tRB+2LB),

RB = 1,0,

LB = 0,001.

G. SEPARATING COMPARATOR

The procedure below can be used to implement the digital device, the separation of the comparator delay. Digital dividing the comparator is included in all embodiments of the invention described above. Dividing the comparator is responsible for making decisions about the division. In other words, it decides when to perform the indication operation of the device to which it is connected.

Digital model of the moving contact cylindrical Electromechanical devices must simulate the Electromechanical characteristics of the cylindrical device. Digital comparator shown in Fig. 3A, was used to develop a digital dividing comparator (see description below).

In Fig. 8A

= angle of rotation,

T= Foy) rotational moment

MS = a constant opposing torque,

I = moment of inertia of the cylinder.

Electromechanical equation for this model is

.

Transforming the equation in discrete formkget the

,

where

,

,

.

If the digital separation of the comparator subject to the following conditions:

If (Mk- MS) < 0, then the followingkzero.

Ifk>Tthen the following kequivalent toTand partitioning is used.

Fig. 8B schematically shows one version of the digital separation of the comparator 30 in accordance with this invention. Input signal dividing comparator is the rotational moment Mk(generated by any of the above devices) and, as shown in Fig. 8B, a limited double inequality-MM<M<+MM, and then the opposite rotational time displacement MC is subtracted from the Mk. Other schemes implement the above equations. Outputkthen compared withTto separate, as noted in condition 2. The gains of the amplifiers "CC", "EE" and "FF" is defined above.

Fig. 9 and Li device in an unusable state, and generates a signal of logic "1" (true) if the device is in working condition. The variable of "0" is input to the signal for the unit and is compared with the upper and lower limits. It should be noted that Fig. 10 shows a typical limits, however, may have selected a different limit values.

If the instantaneous value of the variable is "0" is greater than 0.6, in this case, a signal of logical "1" (true) logic relay protection device with microprocessor control. If this value is less than 0.6, then a logical "0" (false) is formed for logic relay protection device with microprocessor control. In this example, the limits of variation of the variable ranges from 0 to 1.

Specialists in this field understand that the present invention can be implemented in devices and methods that do not exactly match the above. Digital dividing the comparator is used in relay protection for execution in the digital code of the function(s) of the phase comparator. The cylindrical device in the Electromechanical relay is a key element in various devices used in relay protection, including devices determine Yes or minimum voltage, control device and in other special applications. A digital comparator is a phase comparator which can be used for the development of relay devices, such as those discussed above.

Development of the above algorithms digital comparator based on the analysis of a cylindrical device, but the equations have changed. They are not an exact model of the cylindrical device. In fact, the diversity of equations, constants, factors, ranges, etc. that are included in the equations implemented in the device with microprocessor control allows the designer more flexibility to adapt the operation of this device than a real cylindrical device.

1. Device for comparison in real time between the two signals (S1(t) S2(t)), each of which is represented by magnitude and phase, characterized in that it contains means for sampling to obtain a set of samples of each of the two signals at least at two different points in time, and computing means for calculating moment MK+1corresponding to the phase difference of two signals on the basis of samples.

2. The device under item 1, characterized in that ceperly time, selects the reference (S2krepresenting the value of the second of these signals in the same first point in time; allocates count (S1k+1representing the magnitude of the first of these signals in the second time, and selects the reference (S2k-1representing the value of the second of these signals in the same the second time.

3. The device according to p. 2, characterized in that the computing means includes means for obtaining the derivative values B1k, B2k, B1k+1and B2k+1for samples S1to, S2to, S2K+1tool multiplication for multiplying the values B1toB2K+1and multiplying the quantities B2toon B1K+1to get the first piece B1toB2K+1and second compositions B2toB1K+1; and summing means for summing the first and second compositions to obtain the result of the calculation (MK+1) corresponding to the phase difference between the first and second complex vector quantities.

4. The device according to p. 3, characterized in that the values B1toand B2toare using the following ratios:

B1to= FK2[S1k+S1k-1-FK1B1k-1] ,

B2k= FK2[S2yum.

5. The device according to p. 4, characterized in that the constants FK1 and FK2 are defined by the following relations:

< / BR>
< / BR>
where RB and LB are constants.

6. The device according to p. 2, characterized in that the samples S1kand S2kobtained by sampling the voltage or current in the transmission line.

7. The device according to p. 6, characterized in that the signals S1(t) and S2(t) represent the voltage or current varying in a sinusoidal manner, or a combination of voltages and currents.

8. The device according to p. 6, characterized in that it also includes means for using the obtained result of the computation of Mk+1to determine whether there is damage in the specified transmission line.

9. The device under item 8, characterized in that the obtained result of the computation is used to detect interfacial failure in the system of three-phase transmission line, and the samples S1(t) and S2(t) are obtained from interfacial stresses and complex currents.

10. The device under item 8, characterized in that the result of calculation is used for failure detection phase and earth in the system of three-phase transmission line, a S1(t) and S2(t) are obtained from the voltage between phase and earth and complex currents.

11. The device of the definitions of Mk+1to determine the direction of power flow in the transmission line.

12. The device according to p. 11, characterized in that together with the filter is symmetric component output sequence component of the specified filter are input signals of the device.

13. The device according to p. 6, characterized in that it further comprises means for subtracting a predetermined constant (MS) from the received calculation result MK+1and use the difference Mk+1- MS for receiving the signal (k+1), which defines the energy contained in the differential signal S1(t) S2(t).

14. The device according to p. 6, characterized in that it further comprises means for using the obtained result of the computation MK+1in order to determine, exceeds or not the voltage or current in the transmission line specified threshold level.

15. The device according to p. 2, characterized in that it further comprises a scaler for converting the received result of the calculation (MK+1), and the scaler multiplies the result by a specified factor proportional to the sampling period.

16. The method of forming estacionamientos component (I2) current supply system, including getting the samples of these currents to the power system and the use of digital logic circuits to obtain digital values of the symmetric component (I1, I2) in real time, wherein the digital logic circuit includes a delay, amplification elements and summing the elements, United in working condition for the formation of symmetric digital real-time component, and digital logic circuits form a symmetrical components, proportional Ilk and I2k, a I1 represents a current of positive sequence, I2 represents a current negative sequence, the subscript k refers to the digital samples of the respective component.

17. The method according to p. 16, wherein the digital logic circuit forming components Clarke

Ia= 3I1+3I2= a-Ib-1C

< / BR>
moreover, this power supply system includes a first phase (phase-a), the second phase (phase-b) and third phase (phase-C), where Ia is the current in phase-a, Ib is the current in the phase-b and Ic is the current in phase C.

18. The method according to p. 17, wherein the digital logic circuit receives the samples Ia, Ib and Ic; form size Ik-1to obtain the values for IlkIlk-1Ilk-2, I2k, I2k-1and I2k-2.

19. The method according to p. 16, wherein the power system includes a first phase (phase-a), the second phase (phase-b) and third phase (phase-C), and digital logic circuits receive the samples Ia, Ib and IC; form values IakIak-1, Ibk, Ibk-1Ickand ICk-1and then make up combinations of values IakIak-1, Ibk, Ibk-1Ickand Ick-1to obtain values I1kand I2kwhere Ia is the current in phase-a, Ib is the current in the phase-b and IC is the current in phase C.

20. Apparatus for forming non-stationary signals symmetric positive sequence component and the negative symmetric sequence component voltages and currents power supply system comprising means for sampling to obtain samples of these currents of the power system and the digital logic circuit for forming a symmetric positive sequence component (I1) and negative symmetrical component sequences (I2) current supply system, including system elements sirovich symmetric component in real time, wherein the digital logic circuit form a symmetrical components, proportional Ilk and I2k, and I1 represents a current of positive sequence, and I2 represents a current negative sequence, the subscript k refers to the digital samples of the respective component.

21. The device according to p. 20, wherein the power system includes a first phase (phase-a), the second phase (phase-b) and third phase (phase-C), and digital logic schematic form the components Clarke

Ia= 3I1+3I2= 2Ia-Ib-1C

< / BR>
where Ia is the current in phase-a, Ib is the current in the phase-b and IC is the current in phase C.

22. The device according to p. 21, wherein the digital logic circuit includes a first input terminal for receiving samples of the current Ia in phase a and the second input terminal for receiving samples of the current Ib in phase-b, and a third input terminal for receiving samples of the current IC in phase; means for generating values of Ik, Ik-1, Ikand Ik-1; and means for combining the values of Ik, Ik-1, Ikand Ik-1and get the values I1kIlk-1Ilk-2, I2k, I2k-1and I2k-2.

 

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