RU210867U1 - CONVERTER TRANSFORMER TURNING DEVICE - Google Patents

Abstract

The utility model relates to the field of electrical engineering and can be used, in particular, at DC traction substations of railway transport to reduce remagnetization current surges when converting transformers are turned on. The purpose of the utility model is to improve the quality of electrical energy in the power supply system of railway transport, which includes signaling, centralization and blocking devices (SCB) and transformer substations of non-traction consumers. The proposed device allows you to stabilize and reduce the magnitude of the dips on the AC bus voltage (0.4-35) kV when switching on the converter units, accompanied by reversal current surges.

Description

The utility model relates to the field of electrical engineering and can be used, in particular, at DC traction substations of railway transport to reduce remagnetization current surges when converting transformers are turned on.

The purpose of the utility model is to improve the quality of electrical energy in the power supply system of railway transport, which includes signaling, centralization and blocking devices (SCB) and transformer substations of non-traction consumers.

The proposed device allows you to stabilize and reduce the magnitude of the dips on the AC bus voltage (0.4-35) kV when switching on the converter units, accompanied by reversal current surges.

A number of devices are known that provide a reduction in the inrush current of the remagnetization and voltage dips when switching on standby converter units with different equipment. The disadvantage of these devices is the inability to compensate for current surges due to changes in the operating modes of the converter units to stabilize the voltage.

A device is known for eliminating current surges when switching on network transformers, which contains a current-limiting resistor, a triac, and a triac control unit connected in series with the primary winding of the transformer in parallel [1]. The disadvantage of the device is a complex transformer connection diagram, the time required for the multivibrator to go into an open / closed state is (11-12) ms (half a half-cycle of a sinusoid voltage).

A device is known for implementing a method for reducing turn-on currents during multiple switching of a transformer [2], which contains an operational switch connected to the supply network, a switch control panel, a voltage transformer connected to a switch synchronization device having a synchronization unit with the mains voltage, a block for setting the moment of switching off the switch , a block for adjusting the moment of switching on the circuit breaker, control signal generators, the first converter of contact signals to logic ones, one input of which is connected to the normally closed auxiliary contact of the circuit breaker, the second input is connected to the terminal for the trip signal from the circuit breaker control panel, and the outputs are connected through a logic element And with a short circuit connected to the circuit breaker opening drive coil, as well as a second contact-to-logic converter, one input of which is connected to the normally open auxiliary contact of the circuit breaker, the second input is connected to the signal terminal la to turn on from the control panel of the circuit breaker, and the outputs are connected through the logical element AND with another short circuit connected to another coil of the circuit breaker trip drive. The disadvantage of such a device is that when the poles of the circuit breaker open at the calculated time at a given power factor, the same distribution of residual inductions in the cores of the magnetic circuit is not always ensured, since the complete extinction of the arc in the circuit breaker can occur not only during the first passage of current through zero value, but also at the second.

A device for protecting a three-phase transformer against current surges is known, containing a block that sets the value of the intrinsic time of operation of the circuit breaker, a synchronization block, a delay block and an AND logic element, the first input of which is connected to the output of the delay block, the second input is connected to the output of the auxiliary contact, which forms and giving the “on” signal, the third input is connected to the vacuum circuit breaker pole state control unit, and the output of the logic element AND is connected to the input of the pole drive control system, while the output of the synchronization unit is connected to the first input of the delay unit [3]. The disadvantage of such a device is a complex design that includes redundant functional elements, in particular, a set of single-phase instrument transformers, modules for calculating residual induction, measuring transducers, the presence of which entails significant additional costs that are unnecessary for tasks solved at existing railway traction substations.

A device is known for reducing current surges when a transformer is turned on [4], which contains a switch connected to the supply network, a switch control system, a voltage transformer connected to a device for synchronous switching of the transformer. The disadvantages of such a device are the low efficiency of operation with unstable time characteristics of the switches on the 10 kV side, chatter of the KSA contacts, the presence of electromechanical relays in the switch control circuit, this should also include inoperability during the initial switch-on of the transformer due to the lack of a shutdown procedure, and it is also practically not achieved a significant reduction in the inrush current when the transformer is turned on due to the difference in timing of the circuit breaker contacts.

A device is known for shockless switching on of the transformer to idle [5], containing a block of thyristors connected through the input circuits to the phases of the three-phase supply network, and through the output circuits to the winding phases of the three-phase transformer, and a control system that provides connection of the transformer windings to the supply network in two cycles without inrush currents, namely, in the mode of the steady value of the idle current. The main disadvantage of this device is the high cost of the device, commensurate with the cost of a three-phase transformer with a power of (1.0-1.5) MW.

There is a known method of turning on the transformer [6], based on the fact that the primary winding of the power transformer is connected directly to the power source after synchronization, characterized in that a low-power transformer is introduced into the circuit, the primary winding of which is connected to the power source, and the secondary winding through the RL circuit connected to the secondary winding of the power transformer, the synchronization device synchronizes the voltages on the side of the primary winding of the power transformer and the power source. The disadvantages of such a device are: the inability to detect turn-to-turn short circuits in the windings of a power transformer due to the algorithm adopted in it for determining the output of a power transformer in a steady state of operation at idle by the voltage difference at the contacts of an unplugged circuit breaker using a synchronization device; low speed due to the presence of an auxiliary transformer and current-limiting reactors, delaying the process of the output of the power transformer in the steady state of idling.

A device for switching on a three-phase transformer [7] is known, which uses starting resistors, a three-phase diode rectifier, and an inverter. The disadvantage of such a device is the release of heat on the starting resistors, as well as the issue of electromagnetic compatibility of power and microelectronic equipment.

A device is known for turning on a power transformer [8], which uses a three-phase diode rectifier, a reactor. The disadvantage of this device is that this method does not allow to reduce the starting currents below the maximum value.

The closest technical solution (prototype) is a device for reducing current surges when a transformer is turned on, containing a converter transformer, an AC switch and measuring current and voltage transformers, the outputs of which are connected to the control system to synchronize the moment the switch is turned on with the mains voltage, characterized in that it is supplemented with an electric power storage device, the output of which is connected to the input of a bidirectional DC-AC voltage converter, the output of which is connected to the substation buses, while the current and voltage sensors connected to the control system are installed at the output of the storage device, and current transformers are installed at the output of the converter, the outputs of which connected to said control system. [4].

In the prototype, the technical result of reducing remagnetization current surges and voltage dips is ensured by fixing the time at the moment of disconnection relative to the sinusoid of the supply voltage and turning on the backup converter units at the previous time.

The proposed device can be used at DC traction substations with two or more converter transformers, an automatic on-off system for backup converter units, where the effect of reducing the remagnetization inrush current by devices previously developed according to the prototype is not achieved.

The device for switching on the converter transformer provides an instant reduction in voltage dips and remagnetization currents by stabilizing the pre-accumulated electrical energy on the buses (0.4-35) kV, by compensating for the magnetization current surge of transformers (Fig. 1).

The technical result is ensured by controlling the operating modes and regulating the power of the storage device using sensors for measuring currents and voltages connected from the high voltage side of the converter transformers.

In FIG. 2 shows a diagram of a device for switching on a converter transformer.

The claimed device consists of an electrical energy storage device 1 (Fig. 2), sensors for measuring currents and voltages of the electrical energy storage system 2, 3, a DC-AC voltage converter 4, a rectifier converter 5, a control system 6, a converter transformer 7, an AC switch 8 , current transformers 9, 10 and voltage 11.

The control of the operating modes and the change in the power of the electric energy storage device 1 is carried out by the regulation system 6 connected to the medium voltage buses through current transformers 10, 11 and voltage 12 by means of a DC/AC voltage converter 4. Current sensors 2 and voltage 3 are connected to current transformers 9, 10 and voltage 11, respectively.

Implementation of the operation of the proposed device is carried out using the control system 6, which remembers the time of switching off the converting unit and controls the operating modes of the electric energy storage device and power, which makes it possible to implement current compensation depending on the discharge or charge, based on the measurement of the effective and instantaneous values of current and voltage, the degree of charge of the storage devices and the depth of their discharge.

In the charge mode, based on the implemented control algorithm, when current sensors 2 and voltage 3 are fed through current and voltage transformers 9, 10 and voltage 11, the current and voltage values of the control system 6 generate a signal through the DC/AC voltage converter 4 to charge the electric energy storage device 1 and compensate voltage drop and current surge.

In the discharge mode, the power of the storage 1, through the DC/AC voltage converter 4, is supplied to the tires.

In FIG. Figure 3 shows the algorithm of the device operation, illustrating the control of operating modes. The following designations are used:

u _m - instantaneous voltage dip;

i _m - instantaneous value of the remagnetization current inrush;

u _{m const} - setting value of the voltage dip in the storage of electric energy;

i _{m const} - setting value of the inrush current remagnetization in the storage of electrical energy.

u _{m sne} - instantaneous value of the voltage of the electricity storage system (SNE);

u _{m res SNE} - instantaneous value of the discharge voltage SNE;

i _{m res SNE} - instantaneous discharge current SNE;

u _{m charge snne} - instantaneous charge voltage SNE;

i _{m charge SNE} - instantaneous charge current SNE;

The charge-discharge mode of the energy storage device is carried out when the voltage dip exceeds the specified voltage level and the remagnetization current surge occurs (Fig. 3). Control in the charge and discharge mode is based on the analysis of instantaneous values of voltage, current, by introducing settings for the maximum voltage dip and current surge u _{m const} , _{im const} .

The advantage of the proposed device for switching on converter transformers with an electric energy storage device is the limitation of the magnetization reversal current by compensating it with the storage current and reducing the voltage dip.

Bibliographic list

1. Pat. SU (19) 1269755 (11) A3 H02N 9/02 device for eliminating current surges when switching on network transformers / Tamás Fachadi, Lajos Torgni No. 3564997; Claimed 3/3/1983; Published 11/07/1086. Bull. No. 41.

2. Pat. RU (11) 2093943 (13) C1 IPC N02N 9/02 Method for reducing current surges during multiple switching of the transformer / V.A. Kuzmenko Leites L.V., Lozovsky N.A., Lurie A.I., Panibratets A.N., Pindak I.A., Rabinovich V.L., Chuprikov B.C. No. 94014785/07; Claimed 04/20/1994; Published 10/20/1997.

3. Pat. RU (11) 97223 (13) U1 MPK N02N 9/02 Three-phase transformer surge protection device / A.A. Nikolaev, G.P. Kornilov, A.S. Karandaev, T.R. Khramshin No. 2010112689/07; Claimed 04/01/2010; Published 08/27/2010. Bull. No. 24.

4. Pat. RU (11) 108233 (13) U1 IPC H02N 9/02 Device for reducing current surges when the transformer is turned on / V.A. Kvashchuk, N.M. Lapenko, M.A. Karabanov No. 2011108012/07; Declared 03/02/2011; Published 09/10/2011. Bull. No. 25.

5. Pat. RU (11) 127270 (13) U1 MPK N02R 13/00 MPK N02R 13/12 Device for shockless activation of a three-phase transformer / M.I. Altshuller, E.G. Paimurzov, V.M. Pimenov No. 2012144163/07; Claimed 10/16/2012; Published 04/20/2013. Bull. No. 11.

6. Pat. RU (11) 2481692 (13) S2 IPC N02R 9/00 N02R 1/00 Method of switching on the transformer / I.M. Kalinin, V.A. Parshikov, E.Yu. Shulgina, Kuznetsov V.I. No. 2011134955/07; Claimed 08/22/2011; Published May 15, 2013. Bull. No. 13.

7. Pat. RU (11) 2621704 (13) S1 MPK N02M 1/16 Device for switching on a three-phase transformer / V.I. Vishnevsky, E.G. Paimurzov, V.M. Pimenov, S.G. Makarov No. 2016113982; Claimed 04/11/2016; Published 06/07/2017. Bull. No. 16.

8. Pat. RU (11) 2715047 (21) C1 MPK N02M 10/44 Device for switching on a power transformer / V.S. Klimash, R.R. Nimatov No. 2019134975; Claimed 10/30/2019; Published 02/26/2020. Bull. No. 6.

Claims (1)

A device for switching on a converter transformer, containing a converter transformer, an alternating current switch and measuring current and voltage transformers, the outputs of which are connected to the control system for synchronizing the moment of switching on the switch with the mains voltage, characterized in that it is supplemented with an electric power storage device, the output of which is connected to the input of a bidirectional converter constant-alternating voltage, the output of which is connected to the buses of the substation, while at the output of the drive there are current and voltage sensors connected to the control system, and at the output of the converter there are current transformers, the outputs of which are connected to the said control system.

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