SU796975A1 - Device for serviceability testing of protection circuits of three-phase type - Google Patents

Description

I

The invention relates to electrical equipment and can be used to monitor the operability of relay devices; protection.

A device is known for monitoring the reliability of the protection circuits in a three-phase utility, containing three summations. filters of the inverse and zero sequences, two reacting elements, the logical element OR, and the element of time. The device is connected to the outputs of the sensing protection blocks l.

A disadvantage of the known device is that it does not control the operability of the conversion units (limiting amplifiers) of measuring relays.

 The closest to the proposed technical essence is a device for monitoring the operability of three-phase protection circuits, which contains three subtraction elements, three two-wavelength upper conditions, and a reactive element | 2;

However, the known device controls only the health of voltage circuits and does not control. {Health of current circuits, as well as sensing and transforming units of measuring protection relays.

The purpose of the invention is to increase the reliability of protection by monitoring the sensing and transforming units of the measuring relays and the possibility of monitoring current circuits.

This goal is achieved by the fact that in a three-phase protection circuit control device made in the form of three identical sets of measuring relays with elements comparing the phases of the generated signals, containing three subtraction elements, three full-wavelengths and a reacting element, | the rectifier input is connected to the outputs, subtraction elements, and the outputs of the switches are connected in parallel with each other and connected to the input of the reacting element, the output serves as the output of the device, three phase-sensitive blocks are additionally introduced, and the first inputs of the first, second and third phase-sensitive blocks are connected to the outputs conversion units of the same name of the first, second and third sets, respectively, of the relay, the first input of the first phase-sensitive unit is connected to the second input of the third faoch unit, the first input of the second phase-sensitive unit is connected to the second input of the first phase-sensitive unit,

the first input of the third phase-sensitive unit is connected to the second input of the second phase-sensitive unit, the inputs of the first Subtraction element are connected to the outputs of the first to the second phase-sensitive blocks, the inputs of the second subtraction element are connected to the outputs of the second and third phase-sensitive blocks, the inputs of the third subtraction element are connected to the outputs of the third and first phase-sensitive blocks. . . ,

In addition, in order to prevent a false failure signal of protection in the case of an asymmetrical short circuit in the primary network, a time element is added to the monitoring device, the input of which is connected to the output of the response element and its output is the output of the device.

The drawing shows a structural diagram of the proposed device with respect to:, to the control of the health of the distance protection circuits.

The device contains zashshimuyu

line 1 with switch 2 and current transformers 3, transformer 4 of the voltage. CH, measuring relays 5-7 of co-current, each of which consists of receiving blocks 8, 9, 1 of the forming blocks (limiter amplifiers) 10, 11 and comparison element 12 the phases of the signals, the logic block 13 of protection, the devices 14, 15 control the health of the protection circuits, each of which contains phase-sensitive blocks 16-18, elements 19-21 subtraction, full-wave outputs 22-24,

reactive element .25 to element 2 time.

Relays 5-7 resistance, 51 measuring the organs of one of the stages of protection, the same. and have equal settings.

The control device 14 operates as follows.

In the normal symmetric mode of operation of the protected line 1 and the good condition of the current transformers 3 and the transformers 4, the voltages and their secondary currents and voltages supplied to the relay 5-7 are symmetrical and form direct sequence syrtemms.

Since the relay .5-7 resistance is the same, and their settings are equal,. the values of the signals at the outputs of the sensing units 8 are associated with the values of the currents and voltages connected to them with the same linear relative ratios. Therefore, the signals at the outputs I perceive blocks 8 are symmetrical and shifted in phase relative to each other at an angle of 120 °. The signals at the outputs of the conversion units (limiter amplifiers) 10 are shifted to the same angle relative to each other.

 The signals at the outputs of phase-sensitive blocks 16-18, proportional to the phase shift angle between the signals fed to their inputs, are equal to each other. Consequently, the values of the signals at the outputs of the elements 19-21 of the subtraction and at the outputs of the outputs 22-24 are zero. The reactive element 25 is in an inoperative state, and there is no signal at the output of the control device 14.

In case of damage either in the current circuits, or in the voltage circuits, or in the receiving unit 8 or the transforming unit (amplifier-limiting device) 10, any resistance relay, leading to a change in phase shifts between the signals at the outputs of the conversion units ) 10, violates the equality of the values of the signals at the outputs of the phase-sensitive blocks 16-18. The values of the signals at the outputs of the subtracting elements 19-21 and the signal at the input of the reacting element 25 become different from zero. Under c: with the action of this signal, the reacting element 25 is triggered and through the element 26 of time gives a signal / i malfunction.

The response of the reactive element 25 can occur not only when the protection circuits are damaged, but also when the primary currents and voltages are violated as a result of short circuits. The prevention of a false alarm is provided by a time element 26 with a lag in time.

exceeding the duration of the short circuit. If the time element 26 in the control device 14 is absent, then a starting element is needed, which produces a short circuit and blocks the signal supply by the control device 14.

The control device works in a similar way, connected to the outputs of the conversion units (limiter limiters) 11 and controlling the detection of the sensing units 9 and conversion units 11.

You can use one device for monitoring the health of the protection circuits in a three-phase design. In this case, the connection of the proposed device to the controlled circuits (outputs of the conversion units 1O or 11) can be made by any known method, for example, using an automatic switch.

Thus, the proposed monitoring device provides increased reliability of protection by monitoring the sensing and convertible measuring relay units and makes it possible to monitor current circuits and voltages.

Formula inventions

Claims (2)

1. Device for protection of the protection of a three-phase protection circuit made of three identical sets of measuring relays with elements comparing the phases of the generated signals, containing three elements of subtraction, three full-wave rectifiers and a reacting element, the inputs of the detectors connected to the outputs of the elements of the subtraction and the outputs of the inverters are connected in parallel with each other and are connected to the input of the reacting element, the output of which serves as the output of the accelerator, characterized by By the fact that, in order to increase the reliability of protection by monitoring the sensing and transforming units of the measuring relays and the possibility of monitoring current circuits, three phase-sensitive units are additionally introduced, the first inputs of the first, second and third phase-sensitive units being connected to the outputs 10 converting units of the same name of the first, second and 1 relay sets, the first input of the first phase-sensitive unit is connected to the second input of the third phase-sensitive unit, the first input of the second phase-sensitive unit is connected to the second input of the first phase-sensitive unit, the first input of the third phase-sensitive unit is connected to the second input the second phase-sensitive; block, the inputs of the first; subtracting elements | are connected to the outputs of the first and second phase-sensitive blocks, the inputs of the second subtraction element are connected to 25 outputs of the second and third phase-sensitive blocks, the inputs of the third subtraction element are connected to the outputs of the third and first phase-sensitive blocks. thirty 2. The device according to claim 1, so that, in order to prevent a false alarm about protection failure during an asymmetrical short period in the primary network, into it The 3S additionally introduces a time element whose input is connected to the output of the regulating element, and its output is the output of the device. 40 Sources of Information taken into account during the examination 1. USSR author's certificate for application number 273О868 / 24-07, cl. H 02 H 3 / O4, 02.27.79. 4J 2. Fedoseev A. M. Relein protection electrical systems. M., Energie, 1976, p. 284, fig. 4-58.