SU1603475A1 - Device for protecting three-phase synchronous generator against asymmetric shorts - Google Patents

Abstract

The invention relates to electrical engineering and can be used for protection against internal and external asymmetrical short circuits of three-phase synchronous generators. The purpose of the invention is to increase the reliability of the protection operation by expanding the functionality. For this purpose, a second threshold body is introduced into the device, which regulates the amount of negative-sequence power with external asymmetrical short-circuits. 1 il.

Description

The invention relates to electrical engineering and can be used to protect against internal and external asymmetric short circuits (SC) of synchronous generators used as autonomous sources of power supply.

The aim of the invention is to increase the reliability of operation by expanding the functionality.

The drawing shows a functional diagram of the device.

Current transformers 1 and 2 voltages are connected on the phase output side of a three-phase generator. Secondary windings of current transformers 1 are connected to the inputs of the negative sequence current filter 3 (FTSP) ,. and the secondary windings of the voltage transformers 2 are connected to the inputs of the filter 4 of the negative-sequence voltage (TNF), output

which through Phaser 5 is connected to one input of multiplier 1, the other input of which is connected to the output of the FTOP 3. The output of multiplier 6 is connected to frequency filter 7, the output of which is connected to inputs of inverter B and first threshold organ (A01) 9. Output of inverter 8 through the second threshold authority (P02) 10 is connected to the input of the element 11 time (EV). The output of the HOI 9 is connected to the input of the first output organ (BOJ) 12, and the output of the ЭВ 11 is connected to the input of the second output organ (В02) 13.

The device works as follows.

With an asymmetrical short-circuit of a synchronous generator, a signal appears at the output of the FTOP 3 proportional to the current of the negative sequence of the generator. At the output of a FNP4, a signal appears proportional to the voltage

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negative sequence on the generator leads, shifted relative to the current by an angle determined by the resistance of the negative sequence. At the output of the phase shifter 5, the signal arriving at its input will shift by the same angle and coincides in phase with the negative sequence current of the generator.

With an internal short circuit at the output of multiplier 6, the signal proportional to the power of the negative sequence has a positive constant component. At the output of the low-pass filter 7, the signal is proportional to the average value of the negative-sequence power, i.e. The constant component of the harmonic signal at the output of the multiplier 6. When the setpoint of the first threshold organ P01 is exceeded, the protection device triggers and sends a signal to turn off the generator and shut down. At the output of the inverter, there is a negative polarity signal and the threshold organ. vaet.

With external asymmetrical K, the direction of the current through the primary current transformers is reversed and, accordingly, at the output PTAP 3, the polarity of the signal is reversed. Hence, at the output of the low-pass filter, the constant power component of the negative sequence has a negative value, and at the output of the inverter the signal is positive, therefore P02 is triggered and, with a time delay specified by EV11, the protection device through В02 acts on the generator automatic synchronous function. generator asymmetric external or internal short circuit, which achieves the goal. In addition, to protect against asymmetrical internal damage, current transformers are not required to be installed on the side of neutral leads of the generator stator winding.

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Claims (1)

Invention Formula A device for protection of a three-phase synchronous generator against an asymmetric metric short circuit, containing current transformers and voltages with leads for switching the stator windings of the generator from the side of the phase terminals, reverse current filters and reverse voltage voltages whose inputs are connected respectively to current and voltage transformer outputs, a frequency filter, a phase gap, a time element, as well as serially connected first threshold and output elements, characterized by m, that, in order to expand the functional capabilities of 30 m, the second threshold organ, the inverter, the multiplier and the second output organ were additionally introduced, the negative sequence current filter output is connected to the first input jr of the multiplier, to the second input of which the phase shifter is connected to the output of the negative sequence voltage filter, the output of the multiplier is connected via a frequency filter to the combined inputs of the first threshold organ and the inverter, the output of which through serially connected second thresholds bd body and the time element is connected to the input 45 of the second output body.