SU1156188A2 - Device for protection of installation with rectifiers connected in parallel - Google Patents

Abstract

DEVICE FOR PROTECTION OF INSTALLATION WITH PARALLELALLY INCLUDED WITH REMOVAL ON AUTH. No. 1101.962, characterized in that, in order to expand the functionality, a fourth transducer functional current converter to voltage is introduced, and the transformer is provided with an additional winding, the primary winding of the fourth transformer functional current transformer for voltage is designed to be connected to the first phase power supply wire the second rectifier, - and the secondary winding is connected between the junction point of two opposite terminals of the secondary windings of the first and second trans ormatornyh functional current-to-voltage converters and the first vshodom additional transformer winding, a second terminal which is connected to the junction of the same name output transformer primary winding and one of the terminals of the third transformer (A functional transducer current to voltage.

Description

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00 1 The invention relates to relay protection and emergency control automation and is intended for. detection of damage in installations containing a power source operating on parallel-connected rectifiers. According to the main auth. No. 1101962 a device for protection of a system with parallel-connected rectifiers is known, containing three transformer functional current-to-voltage converters, the primary windings of the first and second of which are intended to be connected, respectively, to the first and second phase wires of the power supply network of the first rectifier, and the secondary windings are connected to the executive protection unit, a transformer, a rectifying bridge, a reacting organ, an expander and pulses, a shaper of positive and negative pulses, an AND element, an RC chain and a resistor, and the primary winding of the third transformer functional converter is intended to be connected to the third phase conductor of the power supply network of the second rectifier, while the splicing node is designed as a transformer, the primary winding of which is connected to the secondary windings of all transformer functional converters connected in series, the authorization of the winding is connected to the input of the rectifying bridge , the alarm generation unit is designed as a pulse expander, the output of which is the output of the alarm generation unit, and the input is connected to the output of element I, the first input of which is connected to the output of the rectifying bridge through a reactive org, and the second input is connected to the RC chain, connected to the output of a positive and negative impulse generator, whose input is connected to one of the input poles of a rectifying bridge connected to its initial negative pole via a QlJ resistor. The disadvantage of the prototype is that it is not triggered for asymmetric damages at the entrance (tires) of the second mitels. 8 The purpose of the invention is to expand the functionality of the device by detecting interphase damage at the input of the second rectifier. The goal is achieved by introducing a fourth transformer functional current converter into voltage into a device for protection of the installation with parallel-connected rectifiers, and the transformer is provided with an additional winding, the primary winding of the fourth transformer functional current-voltage converter being connected to the first phase voltage. the power cable of the second rectifier, and the secondary winding is connected between the junction point of two opposite terminals of the secondary a coil of the first transformer and the second functional current-to-voltage converters and a first terminal of an additional transformer winding, a second terminal which is connected to the output point of the same name of the compound of the transformer primary winding and one of the terminals of the third function converter transformer current voltage. I Monitoring the current in the first phase at the input of the second rectifier and converting it to a voltage proportional to it using the additionally introduced fourth transformer, as well as summing it up with voltages proportional to the currents in the first and second phases at the input of the first rectifier, allows and, using the additionally introduced winding in the summing transformer on its secondary winding, select a signal equal to the unbalance voltage in case of external short circuits on the load. In case of internal damages, including two-phase short circuits, on the buses of the second rectifier, a voltage is obtained that is proportional to the fault current, under the influence of which the protection is activated. Due to the counter-switching of the primary and additional windings of the summing transformer, in which counter-directed flows are created, proportional to the sum of the voltages of the existing "windings of the fourth and first transformers, under normal conditions the induced voltage on the secondary winding of the summing transformer is zero, and with external short circuits x unbalance voltage, which eliminates the false operation of protection under normal conditions and external short circuits. FIG. 1 shows a block diagram of the proposed device; 2 shows a circuit for generating a working signal with two-phase short-circuits at the input (on buses) of the second rectifier, I Device for protection of the installation (figure 1), consisting of a power supply 1, operating through parallel-connected rectifiers 2 and 3 for common load 4, contains three transformer current-to-voltage converters (trans-reactors) 5, 6 and 7 with magnetic cores from magnetic-dielectric; primary windings of the first 5 and second 6 trans-reactors are intended to be connected to the first and second phases at the input first issue capacitor 2, the primary winding of the third transreactor 7 is intended to be included in the third phase at the input of the second rectifier 3, transformer 8, rectifier bridge 9, reacting body 10, element 11, pulse expander 12, executive unit (output) 13, resnetor 14, shaper-15 positive and negative pulses, RC circuit 1.6, 17, resistive divider 18, 19, with which the trigger level of the pulse expander 12 is set, the fourth transformer function converter 20, the primary winding of which is for installation in the first phase wire of the power supply network at the input of the second rectifier 3, and the secondary winding is connected between the connection point 21 of two dissimilar terminals of the secondary windings of the first 5 and second 6 transreactors and the first terminal of the additional winding 22 of the transformer 8, the second terminal of which is connected to the point 23 of the connection of the same output of its primary winding and one of the terminals of the third transreactor 7, the primary winding of the transformer 8 is connected to connected in series secondary windings of the primary o, the second and third transreactors 5, 6 and 7, and the secondary winding is connected to the input of the rectifying bridge 9, the output of which is through the reacting element 10, the first input of the element 11, the expander 12 pulses connected to the actuator 13, the resistor 14 is connected to one from the input poles of the rectifying bridge 9 and its output negative poles and through the shaper 15 positive and negative pulses, the RC-chain 16, 17 is connected to the second input of the element 11. The device works as follows. For an external short circuit, at load 4, which is a symmetrical three-phase short circuit on the variable side of rectifiers 2 and 3, the sum of the currents flowing through the primary windings of the transreactors 5, 6, 7 and 20, at the input of the first 2 and second 3 higher The drivers are zero. The sum of the secondary voltages of transreactors 5, 6, and 7, which constitute the first half protection set, detected on the primary winding of the transformer 8, is equal to the unbalance voltage of transreactors 5, 6, and 7. The sum of the secondary voltages of transreactors 7, 6, 20, which constitute The second half-set of protection, located on the additional primary winding 22, is equal to the unbalance voltage of transreactors 7, 6, 20. A signal equal to the sum of the voltages of transreactors 5 and 20 in this mode goes to the primary winding and the additional winding 22 of the transformer Ora 8. The resulting magnetic flux in the magnetic core of the transformer 8 is small. The output signal on the secondary winding of the transformer 8 is equal to the unbalance voltage depending on the external short-circuit multiplicity, non-linearity and non-identical magnetization characteristic of transreactors 5, 6, 7 and 20. The greatest unbalance voltage will be at the external short-circuit current at the load, when transreactors 5, 6, 7 and 20 operate outside the linear region of the magnetization characteristics of their cores. In this case, the secondary winding of the transformer 8 exhibits an unbalance voltage, which is three times the frequency, compared to the frequency of the fault current.

Therefore, the duration of the output pulses of the generator 15 positive and negative pulses is three times less than the duration of the corresponding pulses with internal damage to rectifiers and on their tires. The constant time of the KC circuit 16, 17 is chosen so that during the duration of the positive pulse at the output of the driver 15 when the unbalance voltage is reached, the capacitor 17 does not have time to charge up to the threshold of the expander 12, even if the reacting body 10 is activated, the response the expander 12 pulses and the Executive unit 13 does not occur, since this time at one of the inputs of the element 11 from the output of the RC-chain 16, 17 receives a inhibitory signal.

In case of asymmetrical damages at the input (on the buses) of the second converter, for example, at two-phase short circuits of the first and second phases at the input of the second rectifier 3 (FIG. 2, point K-1), the emergency current flows through the primary winding of the transreactor 20. Under the action of the voltage induced in its secondary winding flows a current branching out at node 21 along two branches m. The current flowing in a circuit composed of successively connected secondary windings of transreactors 20, 6, 7 and an additional primary winding 22 of transformer 8 has created A magnetic flux in a transformer induces a voltage in its secondary winding proportional to the current of a two-phase short circuit. The current flowing in the circuit composed of successively connected secondary windings of transreactors 20 and 5 and counter-connected primary

and additional primary windings. 22 of the transformer 8, creates in the transformer 8 counter-directed magnetic fluxes. Therefore, the resulting magnetic flux and the voltage in the secondary winding of the transformer 8 are determined only by the current flowing in the circuit composed of successively connected secondary windings of the transreactors 20, 6, 7 and the additional primary winding 22 of the transformer 8. Under the action of the voltage on the secondary winding The transformer 8 triggers a responsive body 10 and a shaper 15 positive and negative square impulses. Since the voltage frequency at a two-phase short yamykaniya is equal to the frequency of the main harmonic component of the power supply voltage, for a given duration of positive signals at the output of the driver 15 rectangular positive and negative pulses the capacitor has time to charge to the threshold of the expander 12. When two signals coincide at the first and second input of the element 11, the expander of 12 c, the output unit 13, is triggered. three-phase short-circuit at input x of the first and second rectifiers

Thus, the detection of interphase short circuits at the input (on the buses) of the second rectifier is ensured by introducing a fourth transreactor into the first phase at the input of the second rectifier and additional winding into the summing transformer, switched on accordingly.

Claims (1)

DEVICE FOR PROTECTING THE INSTALLATION WITH PARALLEL SWITCHED RECTIFIERS by ed. No. 1101.962, characterized in that, in order to expand the functionality, a fourth transformer functional current-voltage converter is introduced, and the transformer is equipped with an additional winding, and the primary winding of the fourth transformer functional current-voltage converter is designed to include a second rectifier in the first phase wire of the supply network and the secondary winding is connected between the connection point of the two opposite terminals of the secondary windings of the first and second transformer 's functional transducer current to voltage and a first terminal of an additional transformer winding, a second terminal which is connected to the output point of the same name the compounds of the transformer primary winding and one of the terminals of the third transformer functional current-voltage converter. > < .25