SU762082A1 - Device for protecting the generator of a power unit including generator, transformer and converter - Google Patents

Description

The invention relates to relay protection of electrical systems and can be used to protect the generators of power units, generator-transformer-converter.

A device is known to protect the generator of the power unit generator-transformer-converter, which contains a scheme for comparing the modules of the sixth harmonic voltage at the generator terminals and in the neutral winding of the power unit transformer [ΐ].

The closest in technical essence to the present invention is a device for protecting the stator winding of the generator from single-phase short circuits, which contains the main brake plbcho of the voltage module comparison unit connected to the secondary winding of the voltage transformer installed in the generator neutral and an additional brake arm connected to the sixth filter harmonics and a working arm connected through a third-harmonic filter to the secondary winding of a voltage transformer mounted on the generator terminals (2).

The disadvantages of this generator protection unit generator-trans2

formatting converter are low sensitivity and insufficient coverage, due to the need for detuning from the influence

5 of the third harmonic in the voltage of the Graley valve winding transformer. This voltage is applied to the width of the generating voltage of the power unit through an interwinding capacitance.

Yu (C _t ). Effect on detuning -preobrazovatelya protection depends on the ratio of _an E _T and E C _3a Cp where _sn E, E _sr - EMF third inverter and harmonics generator, _g C - capacitance -nets gene15-valued power voltage. The protection is applicable at power units having an E C _p > _/ E _sn C _t , however, its sensitivity and ¹ coverage area near the neutral vary considerably depending on the angle of control (about) of the converter.

The purpose of the invention is to increase the sensitivity of the protection of the generator, which has capacitors at the terminals ·.

Delivered celbe is achieved by

what's in a known security device

the sixth harmonica filter is connected to

newly introduced current sensor zero

30 sequence capacitors. '

762082

FIG. 1 shows a block diagram of the device; see 2 - the equivalent circuit of the generator-transformer power unit "" Mator-converter. '.

A device for protection of a power unit having "" capacitors 1 connected to the generator voltage buses contains a sixth current harmonic filter

“Capacitors 2, a rectifying bridge 3, an adjustable resistor 4 connected to the unit for comparing the modules of the third harmonics of the voltage in the neutral and on the outputs of the generator 5". - ·

In the equivalent circuit of the generator-transformator- transformation unit 'Vatel (Figure 2) contains the transmitter pulse E emf arising when the valve (six times per power frequency) and _Gt 5 equal Uze ϊ η (ά + y), where E _r ~ the amplitude value of the phase EMF of the valve winding, 2G is the switching angle. In case of impulse effects, it is necessary to take into account the distributed inductance E and the resistance of the stator winding and conduction; l isolation of stator windings on the ground C D. the Input impedance of the generator is determined from the expression

^Ζ βΧ ⁼ bL £ \ G '

where p is the wave resistance of the gene '. rator ............................

V - coefficient of distribution

the waves.

Capacitors, · connected to the generator's waters, shunt the insulation of the stator windings under switching effects, while the current

in the capacitors _t = E _2gp 5 _ί η F and, therefore, on the filter 2 is allocated

 "sixth harmonic, proportional to the angle of regulation of the converter.

The device works as follows. .

The polarity of the rectified voltage of the rectifier bridge 3 in the circuit 5e "era'B" Ioniya voltages' protection select the "wound according to" with the braking voltage -. and counter to the worker that creates an additional braking voltage. The magnitude of this voltage is set by potentiometer 4 and is selected according to the condition; to compensate for the decrease in the braking voltage of the circuit

...... comparison of protection by the third harmonic ^ pry the increase in the angle of regulation of the converter. In the absence of a ground fault, an increase in the angle of regulation of the power supply of the inverters does not trigger the protection, since this causes additional stress on the occurrence of the ground fault in the protection zone (near generator neutral) increases the third harmonic voltage at the terminals (working voltage of the circuit comparisons),

5 and in the neutral generator-, decreases. In addition, it increases, the current in the place'coupling d decreases the current in

capacitors, so the additional braking voltage decreases and

. "Protection works.

The use of the device allows

to protect the generator from single-phase short circuits in the generator-transformer-converter unit with high sensitivity. The installation of capacitors at the outputs of the generators reduces the switching current effects of the converters on the insulation of the stator windings, increases the coverage and the protection sensitivity to short-circuits near the generator neutral by displacing the current divider point in isolation towards the generator leads. Perform protection with a shutdown action

25 generators with a single-phase circuit allows to prevent the development of an accident and reduce the amount of repair work.

Claims (1)

Claim A device for protecting the generator of the power unit generator-transformer from single-phase closures of ¹¹ gauges containing the operating arm of the comparison circuit of the voltage modules, Key to the secondary winding of the voltage transformer installed at the generator terminals, the main tor40. brain arm connected through a third-harmonic filter to the secondary winding of a voltage transformer installed in the generator neutral, and an additional brake arm connected ¹ through a filter of the neck-harmonic; from wild to the same generator with com. pin detector mentioned Sixth harmonic filter ₅₀ is connected to the newly entered ^e zero sequence current sensor capacitors.