SU1455376A1 - Apparatus for differential current protection of conversion transformer - Google Patents

Abstract

The invention relates to electrical engineering, in particular, to relay protection of elements of electrical systems, and can be used to protect power transformers of converter stations that invert the direct current electrical energy into alternating current energy. The purpose of the invention is to increase the stability of the operation by increasing the selectivity in the transient tipping modes of the inverter. This is achieved by the fact that a second adder is additionally introduced into the device for differential protection of the converter transformer, by means of which its periodic component is subtracted from the rectified differential current, and the positive half-waves of the received signal are used for braking the protection. 2 Il. 2 (L

Description

one

The invention relates to electrical engineering, in particular, to relay protection of elements of electrical systems, and can be used to protect power transformers of converter stations that invert electrical energy from direct current into alternating current energy.

The aim of the invention is to noBbmie stability of operation by increasing - selectivity in transient tilting modes of the inverter.

Figure 1 shows the diagram of the device; 2 shows timing diagrams for his work.

The device contains a differential differentiation unit 1, to the output of which the first rectifier 2 is connected, and the output of the latter is connected to the first (non-inverting) input of the first sum-torus 3 operating and braking signal-. fishing The output of the first adder 3 is connected to the input of the reacting authority

4protections. The input of the second rectifier.

5 is connected to the input of the differentiation unit 1 and is intended for connection to the differential current protection circuit. Output of the second rectifier

5 is connected to the first (non-inverting) input of the second adder 6, the output of which through the first amplitude detector 7 is connected to the second

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with

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(inverting) the input of the first sum-frame 3j, thus performing the extraction of operating and braking signals. The output of the first rectifier 2, the second amplitude detector 8 n: is connected to the second (inverting) second adder 6, resulting in the subtraction of the magnitude, the nuclear derivative of the diffracting current.

The device works as follows.

When tilting inverter. (FIG. 2) after saturating the high-voltage-south of the current transformer in one of the terminals in its differential 1; if a unipolar noncirculation current arises, 1d5. The average value of which |

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1; and at the output of the rectifier 5. At the output of the differentiating link, when 1 is switched to the saturation mode, a sinusoidal current is approximately proportional to the derivative of the periodic term, which is reflected by the rectifier 2 and is smoothed by the amplitude, using a fudom detector 8. Scale output amplitude detector current 8) is selected so that the average value (th output current hdd was equal to} 21,. At the amplitude ji input, eTeKTOpa 7 takes place) | 1 variable signal, the amplitude of the polar waves of which is 1. | at „c. The signal is smoothed by the amplitude detector 7 and is used for additional: T-reel braking of the reacting organ 4. The scale of the output current of the amplitude detector is chosen so that the reacting organ is activated.

With a short circuit in the protection zone, the aperiodic component of the current i is much smaller and does not

transcends 1. Therefore, in this mode, a negative signal is generated at the output of the amplitude detector 7, a value (it and no braking signal appears at its output regardless of the scale factor, and there is no braking of the response organ.

Thus, the required sensitivity of the device in case of short-circuit in the protection zone and its detuning from the inverter tilting mode.

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Claims (1)

Invention Formula Device for differential current protection converter 0 of the transformer of the inverting installation, containing the differentiation unit, the first and second rectifiers, the first and second amplitude detectors, the first adder and the reacting organ, 5, the inputs of the differentiation unit and the second rectifier are combined and intended to be connected to the differential current measurement circuit, the output of the differentiation unit through the first rectifier is connected to the first input of the first adder, to the second input of which the output of the first amplitude detector is connected, the output of the first the adder is connected to the input of the reacting authority, the output of which is intended to be connected to the executive protection circuit, characterized in that, in order to increase the stability of the function Increasing the selectivity in transient tilting modes of the inverter, additionally introduced a second adder, to the first input of which the output of the second transmitter is connected, the second input through the second amplitude detector is connected to the output of the first rectifier, and the output to the input of the first amplitude detector. five (-eight - five figure 1 lipaff i i-afli t-thorn iO -i-au  7 id DD iLpaSi. ldg rojy W ( Fi.g