SU817843A1 - Device for comparing phases of several signals - Google Patents

Description

(54) DEVICE FOR COMPARISON OF PHASES OF SEVERAL SIGNALS

The invention relates to electrical engineering, in particular, to relay protection of power systems and can be used to build a power direction relay, a resistance relay and a number of other relays with phase-matching elements. Devices are known for comparing the phases of two or more electrical quantities made using operational amplifiers 1 and 2. A significant drawback of these devices is their complexity in the case of full-wave or double-comparison of several signals, since they either have a large number of signal conditioners used for comparison. , or additional inverters are contained. The closest in technical essence and the achieved effect to the described device is a resistance relay. This device contains shapers of compared values, a block for forming rectangular impulses of coincidence (mismatch) of the signs of instantaneous values of the compared values, and a block for measuring the duration of a pulse of coincidence (mismatch). The unit for forming rectangular pulses is made in the form of successively connected diode selectors of positive and negative signals and a comparator on a differential operational amplifier: the outputs of diode selectors are connected to the poles of the power source through voltage dividers of two resistors, the midpoints of which are connected to the inverting or non-inverting inputs of the operational amplifier and through the diodes to the zero point of the power supply. The above device characterizes. because, for n input values, it performs the comparison function as n values, if the values have not reached their initial preset level (), and can be used when performing a resistance relay with a complex response characteristic. The comparator unit described leads to a partial storage / triggering region of the relay, for example, if the supply chain is interrupted by one of the compared signals 3.

However, if the trigger condition is the coincidence of the polarity signs of the compared values, for example in the case of building a multiphase resistance relay reacting to the coincidence of the polarity signs of the three compensated voltages and a value proportional to the current, the described property of the known device for phase comparison may result in this case to excessive operation.

The purpose of the invention is to expand the functionality of the device by independently adjusting the threshold for each of the compared values.

The goal is achieved by the fact that in the known device, which contains two-pole rectangular pulse shapers according to the number of compared values, each of which is performed on a differential operational amplifier, the resistor is connected to the inverting input, and the non-inverting input is connected to the zero power supply bus, an impulse forming unit of instantaneous value signs of compared values, made in the form of a comparator on a differential operational amplifier, connected by an output To the input of the pulse duration measurement unit, the instantaneous values of the compared values, the output of which is the device output, the inverting input of the first operational amplifier of the full-wave square pulse former is connected to the output of the second operational amplifier, the inverting input of which is connected through the second newly entered resistor to the output of the second operational amplifier the resistor to the output of the third operational amplifier, the inverting input of which is connected through the newly entered the third resistor to the output of the fourth operational amplifier, the inverting input of which is connected through the fourth newly introduced resistor to the output of the first operational amplifier, the outputs of the above-mentioned operational amplifiers are connected to the common point through the additional resistors to the input of the unit of the formation of pulses for the coincidence of signs of the instantaneous values of compared values and for an odd number of compared values, the non-inverting input of the last operational amplifier is connected to the middle point newly inputted voltage divider of two resistors connected between the output of the first operational amplifier and the zero power source bus.

FIG. 1 shows a functional diagram of the device with an even number of compared values; in fig. 2 - with an odd number.

. The device contains, respectively, the first, second, third and fourth differential operational amplifiers 1-4 of two half-period formers of rectangular pulses; the first, second, third and fourth newly introduced resistors, respectively; 5-8, resistors 9-16, block 17

forming the pulse of the coincidence of the signs of the instantaneous values of the compared values, the unit 18 for measuring the duration of the pulses of the coincidence of the signs of the instantaneous values of the values, the voltage divider 19, the resistor 20 and 21 of the voltage divider.

In the initial state of the device, when none of the compared values is supplied or its level is less than the threshold, at the outputs of the operational amplifiers 1-4 of the square pulse drivers, when the power is supplied, the signals normalized by value (output currents by the value o) are polarity +, H -, - (or -, +, -, +) for the circuit of FIG. 1 .. and signals of polarity +, -, + (or-, +) for the circuit of FIG. 2. The resulting signal of the effect of the formers on the comparator 17 is zero for the circuit of FIG. one.

 1o-1o + 1o-1b O

out

and a low insufficient (to operate the comparator) level for the circuit of FIG. 2

 Ifl-1o I,

howled

The switching threshold of each operational amplifier is determined by the ratio of one of the resistances 13-16, to which the input source is connected, and one of the resistances 5-8 of the feedback circuit.

If the value of one (or two) of the signals exceeds a predetermined level, switching occurs with the signal frequency of the polarity of the output signal of one (or two) operational amplifier, to whose input a signal with a high level is applied. At the same time, due to the presence of feedback, other operational amplifiers are switched, and the level of the output resultant signal does not change.

The state with a high level of the resulting signal acquires the circuit only when the signs of all output signals coincide with the levels greater than the threshold ones, and in the circuit of FIG. one

 41,

and in the diagram of FIG. 2

 31o, i.e., xy

out

The output resultant signal (current) of the formers has in this case the maximum value (nio) and serves to select the level of the comparator control signal 17. This level is determined by the ratio of the values of resistors 9–12 connecting the outputs of the rectangular pulse formers to the comparator () and resistive diodes (RCMs) connecting non-inverting and inverting inputs of a zero-bus comparator opamp amplifier:

  n-2.

p c- Wh

For the circuit of FIG. 1 condition of the choice of resistors

| ,.

"VtM

For the circuit of FIG. 2

3 1.

If the number of compared signals is more than 3 (p 3), the device acquires an additional property — the possibility of majorization, i.e., it is possible to ensure operation not only when the signs of all input and signals coincide, but also at a smaller number (ck). This possibility can be realized; by appropriate selection of the comparator switching threshold, which is easily established by selecting the desired RCM resistance ratio.

 llj.

The proposed device has wider functionality due to an independent adjustment of the threshold for each of the compared values.

Claims (3)

Invention Formula A device for comparing the phases of several signals, containing full-wave square-wave pulse shapers according to the number of compared values, each of which is made on a differential operational amplifier, to the inverting input of which a resistor is connected, and the non-inverting input to the zero power supply bus, instantaneous pulse matching unit values of compared values, made in the form of a comparator on a differential operational amplifier, connected by an output to the input rhenium at block measurable pulse duration matcher signs of the instantaneous values of the compared values, the output of which is the output of the apparatus, characterized in that, in order Rasschirennaya functionality . devices due to the independent adjustment of the operation of nopoira for each of the compared values, the inverting input of the first operational amplifier of the full-wave square-wave former is connected through the first again. 5 input resistor to the output of the second operational amplifier, the inverting input of which is connected via the second newly introduced resistor to the output of the third operational amplifier, the inverting input of which is connected through the newly introduced third resistor to the output of the fourth operational amplifier, the inverting input of which is connected through the fourth newly entered resistor to the output of the first operational amplifier, the outputs of the above operational amplifiers through additional resistors are combined into a common point, which is connected to the input of the pulse shaping unit, the coincidence signs of the instantaneous values of the compared values, and for an odd number of compared  The non-inverting input of the last operational amplifier is connected to the midpoint of the newly introduced voltage divider of two resistors connected between the output of the first operational amplifier and the zero power supply bus. Sources of information taken into account in the examination 1. Vanin V.K., Enin A.S. Relay, power directions on operational amplifiers. “Electricity, 1975, No. 7. 2: Vitanov A., Zlatoustov N. Relay of resistance and power direction on integrated circuits “Pr. nauk. Inst energoelektr. Politecknika Wrozlawska, 1977, No. 43, p. 227-234. 3. USSR author's certificate according to application no. 2527409 / 24-07, cl. H 02 H 3/40 1977.