SU506095A1 - Frequency change relay - Google Patents

Description

(54) RELAY SPEED CHANGES IN FREQUENCY

The invention relates to electrical engineering, in particular, to emergency control devices of power systems, and is intended to measure the rate of change of the frequency of the alternating current in the power system.

Analogues of the proposed relays are acceleration relays for power systems developed in the USA (Roemish WR, Clemans iC. L., Loyd LW, Schleif FR). . 1150-1154) and devices on a (W. St. No. 311359 and No. 300923.

The prototype of the proposed relay can be considered the scheme for obtaining the first derivative of the frequency of aiBT. St. No. 311359.

Known relays of the rate of change of frequency, containing an imager with a mains frequency and two NMpulse formation circuits, the first circuit consisting of a series-connected circuit that generates a pulse for setting the counter to zero, a reference frequency generator and a pulse counter, and the second target is an impulse generating circuit measuring the current value of the frequency, the output of both circuits is connected in series with a coincidence circuit, a trigger and a digital-to-analog converter measuring the current frequency value, differential power-exponential, the threshold element and responsive body.

However, the circuits of such relays are very complex, they are characterized by low reliability, insufficient sensitivity and do not provide the necessary accuracy.

The proposed relay differs from the known ones; i4TO for increasing sensitivity and accuracy to the output of the pulse shaper circuit is additionally connected in series with a frequency divider and a circuit generating a measurement pulse of a previous frequency value, the output of which is connected to the input of the circuit generating a measurement measurement pulse of frequency, and between outputs triggers of the memory of the current value of the frequency and the second input of the differential amplifier are additionally connected in series with the coincidence circuit, three ger minute llamas and digital-to-analog lreobrazovatel measuring predschestvuyuschego frequency value, wherein the output circuit, the measurement generating imluls predschestvuyuschego frequency value is coupled to second inputs of the coincidence circuits, input to .podklyuchennym; m triggers 1pam minute predschestvuyuschego frequency value.

FIG. 1 shows the block diagram of the proposed frequency change speed relay; in fig. 2 - time diagram of the relay.

The block diagram of the relay consists of a driver / imgkulsov with a network frequency, frequency divider 2, circuit 3, generating an impulse installation on the pulse counter, circuit 4, generating a measurement of the current frequency, circuit 5, generating impulse measuring the current frequency value, generator 6 the reference frequency, the counter 7 of the pulses, the circuits 8, 9 coincidence, the triggers 10, 11 of the lamp, the digital-analogue converter 12 measure the current frequency, the digital-analogue converter 13 measure the current knowledge The frequency of the differential amplifier 14, the threshold element 15 with an adjustable level of response, the reacting body 16.

The input voltage, which varies with the frequency of the network, is fed to the input of the imaging unit 1, the output of which produces pulses of duration corresponding to one pe. The period shown in FIG. 2, the voltage of ENI6M Ui. The voltage from the output of the imaging device is fed to frequency divider 2, at the output of which the frequency of the input imimisosis is lowered n times (where n is the division factor). FIG. 2, the output voltage of the divider is represented by the voltage U. At the end of the period of the output voltage of the frequency divider 2, the circuits 4 and 5 form short pulses and measured actual and current frequency values.

The iB of the end of the neyrode of the output voltage of the driver / circuit 3 produces a short impulse / pulse counter setting to zero. The temporal position of the pulse (o) is chosen such that this pulse follows the time of the measurement pulse of the current frequency value / ,. with a delay of 20 L1x. The impulse / o each period is fed to counter 7, setting it to zero each time. Thus, the counter at the end of the diode contains information about the voltage period. The measurement pulse of the preceding frequency / f is fed to the coincidence circuit 8, the other inputs of the circuit 8 receive a signal from the output of the memory triggers, in which the information about the prevailing frequency is stored. Thus, at time p, information about the pre-frequency (period) value is transferred. At time t, information about the current value of the frequency from the pulse counter is transferred using co-ownership schemes 9 to triggers 11

P L1IATI.

From FIG. 2 it follows that the current and actual frequency values are separated in time by the number of frequency periods corresponding to the division factor of frequency divider 2, which increases the sensitivity of the relay at low rates of frequency change.

The information from trigger 10, 11 is transferred to digital-to-analog converters 12, 13, where it is converted into a constant voltage proportional to the current and previous frequency values. The difference in these gains of the two D / A Converters is detected by a differential amplifier 14.

Thus, at the output of the differential amplifier, a signal is obtained that is proportional to the frequency increment over n periods of the input voltage, taking into account the sign of this increment, which with a definite approximation is a signal proportional to the rate of change of frequency. This signal is fed to the input of the threshold element 15 with an adjustable response level at which the setup is established.

Q but the rate of change of frequency. At the output of the element 15 is included reactive body 16.

The proposed scheme provides for obtaining several settings for speed, switching on in parallel the output of the differential amplifier 14 of several elements 15 and reacting organs 16.

Claims (1)

Invention Formula A frequency change speed relay containing an imager with a mains frequency and two values of pulse shaping, the first ditch consisting of a sequence of a circuit that produces an impulse of setting the counter to zero, a reference frequency generator and a pulse counter, and the second circuit from the circuit producing measurement impulse current value of the frequency, the output of both circuits is connected in series with a coincidence circuit, a memory trigger and a digital-to-analog converter for measuring the current value of the frequency, differential A power amplifier, a threshold element and a reagent organ, characterized in that, in order to increase sensitivity and accuracy, the output of the pulse shaper circuit is additionally connected in series with a frequency divider and a circuit generating a measurement pulse of a prior frequency value, the output of which is connected to the circuit input, which is produced, her pulse measuring the current value of the frequency, and between the outputs of the triggers the memory of the current frequency value and the second input of the differential amplifier are additionally connected in series with a matching circuit, a trigger and a digital-to-analog converter measuring the previous frequency, and the output of the circuit generating the measurement pulse of the actual frequency jump is connected to the second inputs of the matching circuit connected to memory trigger inputs previous frequency value. f J 4 i M j I G - 1f i  g Liir I n I  ) -; I i / -; S i i  I J