SU817785A1 - Frequency relay - Google Patents

Description

(54) FREQUENCY RELAY

one

The invention relates to electrical engineering, in particular to a frequency relay used in relay automation systems that react to changes in frequency in electrical networks x.4J

Frequency relays are known in which auxiliary frequency generators are used to obtain the pick-up setting.

One of the known frequency relays, in addition to the frequency generator, contains phase-sensitive and differentiating elements. The moment of equality of frequencies (response time) in this relay is determined by the equality to zero of the slip speeds of their phases, which is determined after the differentiating element by the zero current or voltage 1.

The disadvantage of such a relay is a large error at a small value of the slip of the controlled frequency, due to the difficulty of detecting a zero current or voltage at a substantially small value.

The second of the known frequency relays contains an auxiliary generator, a phase-sensitive frequency comparison unit and

executive body fixing the equality of frequencies. A feature of this frequency relay is the presence of a transformer connection between the phase-sensitive unit and the generator. Using this communication, the frequency of the signal of the auxiliary oscillator frequency and the generation of a signal for actuating the actuator 2 are performed.

A significant disadvantage of this relay is that the capture of the frequency of the auxiliary generator can be carried out in the frequency band, which determines the significant error of the known relay.

The closest technical solution to the present invention is a frequency relay containing an actuator controlled by a frequency generator, two square pulse formers, one of which is connected to the generator output, and the other having two outputs, direct and inverse, is connected to a source of controlled frequency, a phase automatic frequency control node with two inputs connected to the outputs of the specified drivers and two outputs, one of which is connected to the control input frequency generator, phase-sensitive, three inputs of which are connected to the outputs of the formers. To eliminate the frequency of actuation of the executive body of this relay when the controlled frequency deviates from the setpoint, two integrating elements are introduced into it, a differentiating element, two AND elements, a trigger with separate inputs and a key, while the inputs of the first and second integrating elements are connected to the first and second, respectively; the output node of the phase automatic adjustment, the input of the differentiating element is connected to the first inputs of the elements And, the outputs of the first and second integrating elements are connected to the second inputs of the first and second elements And, the outputs of which are connected to the trigger inputs, and the output of the trigger through the actuator input and through the key is with the control input of the frequency generator. Phase self-tuning of the controlled generator provides high accuracy and speed of this frequency relay, so; as the coincidence of the frequency and phases occurs simultaneously and strictly on the own often controlled generator 3. A disadvantage of the known frequency relay is its multi-element and multiplicity of internal connections leading to a decrease in its reliability. The purpose of the invention is to increase the reliability of the frequency relay. The goal is achieved by the fact that a known frequency relay containing an actuator, a controlled frequency generator, a key, connected to the output of an actuator through the control circuit, and two rectangular impulse drivers connected to the input of the controlled frequency generator, which is connected to the output of the controlled frequency generator, and the input of the other is connected to the source of the controlled frequency, the node of the phase automatic frequency control with two inputs connected to the outputs of the AC These two drivers, one of which is connected to the controlled input of the frequency generator, also contain a differentiating element and an integrating element, connected at the input to the first output of the phase-locked loop node and to the common power supply, and additionally introduced a second differentiating element and the discriminator polarity of the input signals, while the first differentiating element is connected between the second output of the phase-locked loop and the output of the integrating element, the second differentiating the element is connected between the output of the integrating element and the input of the polarity discriminator of the input signals, two outputs of which are connected to two inputs of the actuator. The drawing shows a diagram of the frequency relay. The scheme contains a controlled frequency generator 1, a source 2 of a controlled frequency, drivers 3 and 4, a node 5 for phase automatic adjustment, an integrating element 6, a differentiating element 7 and 8, a discriminator 9 of polarity of the INPUT signals, an executive body 10, a key 11. phase automatic adjustment and the executive body 10 can be performed on the trigger. As key 11, any element with a relay output characteristic can be used. The control circuits of the frequency generator 1 from the node 5 of the phase automatic adjustment and the key 11 can be separate or combined. In order to organize the control action of the node 5 of the phase automatic adjustment and the key 11 on the frequency generator 1, it is advisable to select a part of one of the links of the frequency setting body of the frequency generator. The frequency relay operates as follows. The operating frequency band, which does not cause the relay to operate, is determined by the capture band by the controlled frequency of the source 2 of the frequency of the generator 1 using the node 5 of the phase auto-tuning. Each value of the monitored frequency in the capture band corresponds to a certain value of the phase shift between it and the frequency of generator 1. The relay setpoint is determined by the value of the natural frequency of generator 1 without affecting node 5 of the phase-locked loop. This is equivalent to choosing as the setpoint for the operation of the Bdna of the boundary frequencies of the capture band, when the phase shift between the frequencies of the generator 1 and the monitored source 2 is zero. When sliding the controlled frequency of source 2 to the boundary frequency of the capture zone, determined by the natural frequency of generator 1, the phase shift between the frequency of generator 1 and the frequency of controlled source 2 decreases linearly, approaching zero. The duty cycle of the pulses is reduced at one of the outputs of the trigger of the node 5 of the phase-locked loop, and at the other output of this node increases. The voltage at the output of the low-pass filter formed by the integrating element 6 and the differentiating element 7 increases linearly. At the transition of the controlled frequency of the source 2 of the limiting frequency of the pickup zone (triggering setpoint), the character of the pulse duty cycle at the outputs of the node 5 changes dramatically

phase automatic adjustment. At the output of the integrating element b (the output of the low-pass filter) a front of a sharp voltage drop is formed, and at the output of the differentiating element 8 a pulse of, for example, negative polarity is formed. The generated pulse of the indicated polarity is directed by the discriminator 9, for example, to the first input of the actuator 10, causing it to transition to a steady state corresponding to the transition of the setpoint controlled by frequency.

The executive unit in this state triggers key 11, and the latter, in the activated state, fixes operation of generator 1 at a frequency equal to the setpoint frequency for return.

The finding of the controlled frequency of the source 2 beyond the limit of the setpoint for returning is accompanied by the process of beating of the controlled frequency and the frequency of the generator at the outputs of the node 5 of the phase self-tuning. However, this does not cause the periodicity of operation of the actuator 10 and the key 11. With this sign of the difference and the direction of slip of their phases, each phase match is accompanied by the formation of a sharp drop in voltage at the output of the integrating element 6 (low pass filter) and the generation of a negative polarity pulse by differentiating element 8 .

The discriminator 9 of the polarity of the input signals at the same time generates a signal directed to the same input of the actuator 10, which does not cause it to return to its original state.

The return of the controlled frequency of source 2 to the limit of the setpoint for return is accompanied by a change in the sign of the difference between it and the frequency of the generator, as well as a change in the direction of slip of their phases. Therefore, the very first coincidence of the phases of these frequencies is accompanied by a change in the order of a change in the pulse duty cycle at the outputs of the node 5 of the phase-locked loop and the formation of a sharply increasing front voltage at the output of the integrating element 6. Differentiating element 8 forms a positive polarity pulse from this front, and the discriminator 9 generates a signal sent to the second input of the executive body 10, which causes the executive body and the key 11 to return to the initial state. The key 11 releases the blocking action of the phase locked loop node 5 and the frequency of the generator 1 is captured and held at a controlled frequency.

Adjusting the setpoint for the operation of the frequency relay is controlled by

generator self-frequency 1. The return adjustment is performed by selecting the generator 1 frequency fixed by key 11. The frequency relay operation error is determined by the instability of the generator 1 natural frequency and, if used, the RC generator can be no more than 0.2%.

The response time of the frequency relay is determined by the generation time of the control signal of the differentiating element 8.

Technical and economic efficiency with the use of the invention is to increase the reliability of the frequency relay, as well as to reduce the cost of mass production.

Claims (3)

1. USSR author's certificate No. 111224, cl.-G 01 23/12, 1953. 2. Author's Certificate of the USSR No. 117849, cl. H 01 M 47/20, 1967. 3. USSR author's certificate in application number 26835397 / 24-07, cl. H 01 H 47/20, dated 11/13/78.