SU647791A1 - Arrangement for differential protection of multi-winding trasformer - Google Patents

Description

(54) DIFFERENCIALNS DEVICE PROTECTING A MULTI-WAY TRANSFORMER

The goal is achieved by the fact that a device for differential protection of a multiple-winding transformer, containing 7 transformers, contains current-voltage converters to the secondary windings to which the current-voltage converter is connected, the output of which includes the driver of the working signal, the driver of the brake signal and the first comparison unit, one of the inputs of which connected to the output of the braking signal former; the other of the inputs is connected to the output of the positive half-wave of the operating signal former, the output of the negative half-waves which is connected to one of the inputs of the braking signal generator, and the output of the ac signal of the operating signal generator through the first and second harmonic filters and the module drivers are connected to the first two inputs of the second comparison unit, its third input is connected to one of the outputs of the first comparison unit, the fourth with one of the inputs of the first unit of comparison, and the outputs of the first and second comparison units are connected to the logical element I, equipped with a compensation unit for unbalance currents within the allowable range and voltage one whose inputs are connected to inputs of the comparison unit, and the other input connected to the output of positive half wave shaper operating signal, and an output current unbalance compensation unit is connected to a fourth input of the second comparator block.

The drawing shows a schematic diagram of a single phase differential device. sauiHTbi multiwinding transformer I. The secondary windings of current transformers of 2 arms of protection are connected to the inputs of converters of a current-voltage 3 differential protection devices. The current converter 3 voltage inputs 3 are connected to the inputs of the operating signal generator 4, the braking signal 5, the first comparison block b and the unbalance current compensation unit 7. The operating signal generator 4 has an alternating signal output 8, a negative half wave output 9 and an output of positive half waves W . The output of the variable signal 8 is connected to the inputs of the first harmonic filter 11 and the second harmonic filter 12 of the working signal. The filter outputs are included on the module shapers 13. The outputs of these module shapers are connected to two inputs of the second comparison unit (comparator) 14, the protection input set at the third input is set to the fourth input of the comparator 14 connected to the output of the block to compensate for unbalance currents 7.

The output of negative half-waves 9 of the driver of the working signal 4 is connected to the input of the driver of the brake signal 5. The output of the positive half-waves 10 -

four

with the input of the block to compensate for the unbalance ticks 7. The outputs of the last block and the braking signal generator 5 are connected to the inputs of the first comparison block 6. The outputs of the comparison blocks 6 and 14 are connected to the inputs of an AND 15 logic element.

When a multiwinding transformer is turned on under voltage, when significant magnetizing current surges are possible, the device operates selectively as follows: voltages proportional to the currents of the protection arms are fed to the inputs of the operating signal shaper 4. From the AC output 8, the voltage proportional to

5, a differential current is applied to the filters of the first 11 and second harmonics 12 of the operating signal. The first and second harmonics are rectified by the shapers of module 13 and are fed to the inputs of the second unit of comparison 14, where they are compared and, when

the second harmonic and the first harmonic of the primary current are less than 0.2, the comparison unit is activated (a signal appears at its output).

Since any surge current magnetization this ratio is always greater than 0.2, the device provides a detuning from all types of switching current.

In normal mode, when regulating the voltage of the transformer under load

d, at the output of the block to compensate for unbalance currents 7, which is an inertial link with limitation, a straightened and smoothed unbalance voltage is extracted. It is fed to the inputs of the first comparison unit B and the second comparison unit 14 and

 acts on them in the direction of failure. Since the process of regulating the voltage of a transformer under load is slow (seconds to ten seconds), the unbalance voltage caused by this regulation is always compensated by the output voltage of the unit to compensate for the unbalance current 7. This improves the sensitivity of the differential protection without tuning it off. from unbalance currents due to regulation of voltage 5 or under load.

In the case of an internal short circuit, the protection device is triggered in 20-30 ms, the unit for compensating unbalance currents 7 does not have time to influence the operation of the comparators. The level of limiting the signal at the output of the unit to compensate for unbalance currents 7 is set to the corresponding limits of transformer voltage control. 5 The positive effect of the invention is to extend the functionality and increase the sensitivity of the protection, this allows you to disconnect the damaged multiwinding transformers.

on more paiHiefl stages of development. which reduces saTpatbi on its recovery.

Claims (2)

1. For the number of 203940-24-7, class. H 02 H 3/28. 1972. 2. "Development and research of the differential relay on operational amplifiers, izv. Universities-Electromechanics, 1975, № 7. On from tm.